Symposium CK
ABSTRACTS
Session CK-1 Dielectrics and microwave materials
CK-1:IL01 Ordered Domain Engineering of Ba-based Complex Perovskite Ceramics
XIAO LI ZHU, XIANG MING CHEN, School of Materials Science and Engineering, Zhejiang University, Hangzhou, China
It is an important subject to improve the temperature coefficient of resonant frequency (τf) and thermal conductivity (κ) of microwave dielectric ceramics without reducing the Q×f value. Ordered domain engineering was applied to realize the previous objectives in a series of Ba-based complex perovskite ceramics. With the increasing ordering degree, collaborative optimization of microwave dielectric properties was obtained. The noticeable ordered domain structure with large ordered domains (∼100 nm) and low-energy domain boundaries was revealed in materials with excellent performance. The consequent weakened phonon scattering rises the thermal conductivity. The increased bond covalency and oxygen distortion in ceramics with higher ordering degree were suggested as a cause of enlarged bandgap, which enhanced the dielectric strength. The reduced τf is dominated by the less “rattling” space of the cations in the ordered state by inducing more positive τε. The reduced τf, optimized thermal conductivity, and Q×f value in the present work indicate that the ordered domain engineering could open up a new direction for the optimization of microwave dielectric ceramics.
CK-1:IL02 Controlled Dielectric Properties of 3D-Printed Gyroid Ceramics for Enhanced Dielectric Resonator Antenna Performance
R. BENZERGA1, T. LAVIE1, M. JULIAN1, L. LE GENDRE1, A. SHARAIHA1, F. CHEVIRÉ2, C. LE PAVEN1, 1IETR, Institute of Electronics and Telecommunications of Rennes, University of Rennes, France; 2ISCR, Institute of Chemical Sciences of Rennes, University of Rennes, France
The rapid evolution of wireless telecommunications has intensified the search for advanced dielectric materials and novel manufacturing strategies. In this context, our research explores the dielectric properties of ceramics shaped into gyroid structures using additive manufacturing and commercially available alumina and zirconia materials. By controlling the gyroid geometry, we achieved significant adjustment of the resonators’ effective permittivity from the intrinsic values of the bulk ceramics (32.7 for zirconia and 9.4 for alumina) down to values approaching that of air (1). Experimental measurements closely matched theoretical predictions based on the Maxwell-Garnett Approximation as the proportion of air within the structure increased. To demonstrate the potential of this approach, two dielectric resonator antenna prototypes are fabricated: a conventional bulk alumina antenna and a zirconia gyroid antenna presenting the same effective permittivity. Both prototypes exhibited similar resonance frequencies, confirming the accuracy of our permittivity control, as measured by the resonant cavity method in the gigahertz range. The gyroid antenna achieved a 50% reduction in weight, a key advantage for satellite communication applications. Our accessible measurement techniques provide clear design guidelines, reproducible production of lightweight, high-resolution ceramic components with tailored dielectric properties, thereby broadening the material landscape for next-generation telecommunications devices.
CK-1:IL03 Integration of Functional Materials in LTCC and SiCer Multilayer Substrate Modules
J. TÖPFER1, M. HEIDENREICH1, T. SCHULZ1, B. CAPRARO2, 1Ernst-Abbe-Hochschule Jena, Jena, Germany; 2Fraunhofer IKTS, Hermsdorf, Germany
We have studied the integration of functional materials into LTCC multilayers architectures. We will report on SiCer composite substrates which are fabricated by combining Si wafers and LTCC multilayer systems through cofiring at 900°C, wafer processing, and assembly of the complete module. SiCer composite substrates allow fabrication of MEMS, sensor- and communication modules. A specific LTCC tape material BCT was developed for shrinkage matching. Examples for the integration of functional materials into the LTCC multilayer system include ferrites for integrated transformers, dielectrics for integrated capacitors, and NTC spinels as temperature sensors. We also report on LTCC multilayer modules with integrated magnetic microwave components for satellite communication systems in the Ka-band (26-40 GHz). We studied Sc-substituted M-type ferrites BaMexFe12-xO19. Static magnetic measurements show that both the saturation magnetization and coercivity decrease with x, indicating a reduction of the anisotropy field and ferromagnetic resonance frequency (FMR). The FMR for ferrites with x = 0.5 is at 30 GHz allowing such materials to be used for Kq-band circulator applications. Integration of anisotropic ferrites into LTCC multilayer modules was realized as bulk drop-in components into LTCC cavities. Alternatively, anisotropic ferrite films are obtained by screen-printing or tape casting, subsequent drying in magnetic field and cofiring. Such oriented self-biasing ferrite layers are used in LTCC multilayer microwave components.
CK-1:IL04 Development of High Dielectric Ceramic Filled PTFE Substrates and Design of Compact MIMO Antenna for Sub-6 GHz Band Applications
R. RATHEESH1,2, CH MADHURYA1, J. MANIKANTA1, S. AKSHDEEP1, 1Centre for Materials for Electronics Technology (C-MET), Ministry of Electronics & Information Technology, Government of India, IDA Phase III, Hyderabad, Telangana, India; 2Centre for Materials for Electronics Technology (C-MET), Ministry of Electronics & Information Technology, Government of India, Panchawadi, Pune, Maharashtra, India
Copper cladded PTFE/ceramic laminates are the prime choice for high frequency communication applications considering their tailorable dielectric constant, low dielectric loss, high thermal resistance and excellent thermal stability for applications such as telecommunication, automotive, aerospace, defense etc. Miniaturization is another key requirement in these sectors which positioning these laminates as critical enabler for innovation. In the present work, high dielectric ( r=13.5) and low loss tangent ( tan =0.002) PTFE/ceramic laminates have been developed through a patented SMECH process comprising of Sigma Mixing, Extrusion, Calendering and Hot Pressing. Vaccum lamination technique has been used for cladding 35 thick oxygen free copper foil on to plasma etched PTFE/cearmic lamiantes. X-band waveguide cavity perturbation technique is used for precisely measuring the dielectric properties of the fabricated composite laminates. A compact multiple input and multiple output (MIMO) antenna is designed using High Frequency Structure Simulator (HFSS) for 5G communication applications. The proposed design consists of two element array-based antenna system with each element is having 1x3 array with coaxial feed. Radiating patch array has two step rectangular slots on either side of the patch. Two step rectangular stubs are added parallel to the edge of the patch on both sides. The stubs and slots in the patch increase the bandwidth of the designed antenna. Isolation of the MIMO antenna is improved from -10 dB to -35 dB at center frequency and -16 dB in the frequency band by defected ground structure. The fabricated antenna resonates with an impedance band width from 3520 MHz to 3825 MHz and having 15 dB isolation. Antenna has a high gain of 7.6 dBi with good envelope correlation factor. Measured results are in good agreement with simulations studies.
CK-1:IL05 P-V-L Theory and First Principle Density of States Calculation for Chemical Bond Evaluation of Microwave Dielectric Ceramics
HONGYU YANG, HONGCHENG YANG, ENZHU LI, School of Integrated Circuit Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
The first principle calculation, recognized for its reliability in elucidating the intrinsic correlations between the structure and properties of microwave dielectric ceramics, is often hindered in practical applications due to its inherent complexity. In response, the P-V-L theory, a simplification of the complex chemical bond theory, has emerged as an alternative. This theory establishes a general relationship between lattice vibration modes/chemical bonds and the dielectric constant and loss, offering a robust theoretical framework to uncover the intrinsic microwave dielectric response mechanisms of these ceramics. Nonetheless, the accuracy of chemical bond bonding outcomes within the P-V-L theory is pivotal to the reliable computation of other chemical bond property parameters. Consequently, the validation of chemical bond bonding results in microwave dielectric ceramics is essential to ensure the precise correlation between chemical bond property parameters and microwave dielectric properties. First principle density of state calculations and P-V-L theoretical chemistry bond calculations have been conducted on microwave dielectric ceramic systems that incorporate rare earth ions, exhibiting diverse crystal structures, complexities, and dielectric properties. The prospective application of these two methodologies in evaluating chemical bond bonding results across other microwave dielectric ceramic systems is anticipated, laying a foundation for comprehending the interplay between chemical bond property parameters and microwave dielectric properties
CK-1:L06 Numerical Simulations of AlGaN/GaN-FP-HEMTs Performance for High Frequency Applications
M. KADDECHE1, Z. EDDINE KADDECHE2, 1Department of Electronics and communivations,Faculty of Science and Technology, Djilali Bounaama University of Khemis Miliana, Ain Defla, Algeria; 2Faculty of E.A.S, Kütahya Dumlupınar University, Kutahya, Turkey
The excellent microwave power performance demonstrated in AlGaN/GaN HEMTs (high-electron mobility transistors) results from the combination of high current density with high voltage operation [1], which benefits from the high sheet charge density in these hetero-structures (1013 cm-2), the high carrier mobility (1500 cm2/Vs) and saturation velocity (1.5 × 107 cm/s) in the channel and the high breakdown voltage inherent in the GaN material. However, their reliability still limits their applications in today’s electronic systems. The newly developed field-plated AlGaN/GaN high electron mobility transistors show improved performance due to the electric field reduction in the device channel and surface modification [2]. We report on two dimensional numerical simulations of gate-recessed and field-plated AlGaN/GaN HEMTs where all the important device parameters have been defined, the insulator thickness under the field plate is also an important design parameter to attain higher breakdown voltage, GaN-based FP-HEMTs technology still presents great potential to get good microwave power at high frequency. To our knowledge, this performance constitutes state of the art at 40 GHz for AlGaN/GaN HEMTs.
CK-1:L07 AI-Driven Prediction Model for Material Properties of Multilayer Ceramic Capacitors
HYEJEONG SONG1, MINTAEK SEO1,2, HYUNSEOK KO1, 1Convergence Research Division, Korea Institute of Ceramic Engineering and Technology, Jinju, Republic of Korea; 2Department of Materials Engineering, Gyeongsang National University, Jinju, Republic of Korea
Multilayer ceramic capacitors (MLCCs) are key components for next-generation electronics, but their optimization through traditional trial-and-error is inefficient. To accelerate development, a predictive design framework is essential for achieving high permittivity, low dielectric loss, and long-term stability. We have developed a novel artificial intelligence (AI) model to predict dielectric constant, dielectric loss, and material density based on chemical composition and processing conditions. The core innovation of our approach is a "simulation-informed" methodology; the model integrates high-fidelity theoretical properties derived from first-principles (DFT) calculations with experimental data. This unique fusion bridges the gap between atomic-scale physics and macroscopic performance, enabling more accurate and physically grounded predictions. The model automatically associates theoretical property data with input compositions, enhancing both training and prediction. We expect this AI-driven strategy to create a highly efficient design loop, significantly reducing experimental workload, shortening development time, and lowering costs for advanced MLCCs.
CK-1:L08 Influence of Gamma Irradiation on the Structure and Dynamics of the Crystal Lattice of Solid Solutions of Ferrites Co1-xZnxFe2O4 (x = 0, 0.25, 0.5, 0.75, 1)
H. RYMSKI, Scientific and Practical Center for Materials Science of the National Academy of Sciences of Belarus, Minsk, Belarus; M. BUNEVICH, Belarusian State University of Informatics and Radioelectronics, Minsk, Belarus; I. LAGUTSKIY, ATOMTEX SPE, Minsk, Belarus
Solid solutions of spinel ferrites Co₁₋ₓZnₓFe₂O₄ (x = 0, 0.25, 0.5, 0.75, 1) were synthesized via a modified sol–gel route. X-ray diffraction, Raman spectroscopy, and dielectric spectroscopy were employed to assess the impact of γ-irradiation at 2.5, 5, and 10 kGy on structure and lattice dynamics. The cubic lattice parameter increases from a = 8.3768 Å in CoFe₂O₄ to a = 8.4297 Å in ZnFe₂O₄, consistent with a transition from an inverse (CoFe₂O₄) to a normal (ZnFe₂O₄) spinel. The average crystallite size and microstrain decrease from D = 55.952 nm and ε = 0.988 for CoFe₂O₄ to D = 25.002 nm and ε = 0.255 for ZnFe₂O₄. Within this dose range, lattice metrics change only weakly under ionizing γ-radiation; nevertheless, Raman signatures confirm the formation of radiation-induced defects and a redistribution of cations between tetrahedral (A) and octahedral (B) sites in the spinel lattice.
CK-2 Ferroelectric, piezoelectric, pyroelectric, and ferroelastic ceramics
CK-2:IL09 Solid-state Formation Reactions and Dopant Incorporation in the Complex Perovskite Piezoceramic (Ba,Ca)(Zr,Ti)O3
J. KORUZA1, A.M. PAULIK1, A.S. STECHER1, O. CLEMENS2, M. WIDENMEYER3, 1Institute for Chemistry and Technology of Materials, Graz University of Technology, Graz, Austria; 2Institute for Materials Science, Chemical Material Synthesis Group, University of Stuttgart, Stuttgart, Germany; 3Department of Materials and Earth Sciences, Technical University of Darmstadt, Darmstadt, Germany
Emerging electroceramics with complex multi-ionic compositions increasingly challenge the boundaries of solid-state processing methods, often resulting in chemical heterogeneities, secondary phase formation, and problems with repeatability. This is particularly evident in the field of lead-free piezoceramics, where compositions with five or more metallic cations are often considered in order to improve functional properties through phase boundary and defect engineering [1]. Here, we present a study of the formation reactions and microstructure evolution in the lead-free piezoceramic (Ba,Ca)(Zr,Ti)O3 system, using various solid-state processing routes. We report the finding of new intermediate oxycarbonate phases and demonstrate approaches for secondary phase removal and improved material homogeneity [2]. Moreover, we investigated the role of additional acceptor and donor ions on the microstructure formation and functional properties, paving the way for new doping strategies using Fermi level engineering [3].
[1] Acosta et al., Appl Phys Rev 4, 041305 (2017); [2] Paulik et al., J Eur Ceram Soc 46, 117736 (2026); [3] Klein et al., J Electroceram 51, 147 (2023).
CK-2:IL10 Lead-free Piezoelectric Ceramics Based on (K,Na)NbO3: From Bulk Materials to Thin Films
JING-FENG LI, State Key Laboratory of New Ceramic Materials, School of Materials Science and Engineering, Tsinghua University, Beijing, China
Piezoelectric materials are integral to a broad spectrum of electronic devices, such as sensors, transducers, and actuators. From the standpoint of environmental sustainability, the development of high-performance lead-free piezoelectric ceramics has emerged as a critical priority. (K,Na)NbO3 (KNN) has been recognized as one of the most promising lead-free candidates, attracting extensive research attention over the past two decades. Through phase boundary engineering and multiscale structural design, the piezoelectricity of KNN-based ceramics has reached levels comparable to, and in some cases surpassing, those of conventional Pb(Zr,Ti)O3 (PZT)-based ceramics. While the majority of research has focused on enhancing the piezoelectric properties of KNN-based bulk ceramics, recent advancements have stimulated growing interest in thin films for miniaturized devices. This presentation will first review the progress in developing KNN-based ceramics with enhanced piezoelectricity and improved temperature stability. Subsequently, I will present the latest advances in KNN-based thin films exhibiting large linear piezoelectric strains at high frequencies. Finally, I will show some application examples and offer perspectives on the further development of lead-free piezoelectric ceramics.
CK-2:L11 Electric Properties of Single-crystalline Ferroelectric Oxide Thin Films Transferred onto Polymer Membranes
HIROAKI NISHIKAWA, B.O.S.T. Kindai University, Kinokawa, Japan
Since the pioneering work by Nomura et al. on transparent flexible thin-film transistors using oxide materials, research on flexible oxide devices has advanced rapidly. Most studies in this field employ polymer membranes as flexible substrates, which requires low-temperature processing due to their limited heat resistance. A common approach has been the exploration of amorphous oxide materials, which can be deposited at room temperature and exhibit properties such as high carrier mobility. This has led to significant progress in applying amorphous oxide semiconductors to various flexible devices. Conversely, traditional applications of oxide materials often rely on their ability to integrate diverse electronic functions, which requires epitaxial thin films due to their strong anisotropy. However, the high process temperatures required for epitaxial growth have thus far precluded their use with flexible polymer membranes. This underscores the need for novel processes to enable traditional oxide material applications in flexible devices. In this study, we propose a transfer process for epitaxially grown functional oxide thin films, initially deposited on suitable substrates, to flexible polymer membranes.
CK-2:L12 Synthesis and Characterization of Silver Niobate-based Thin Films
LIANG SHU, J.F. LI, Tsinghua University, Beijing, China
As a typical lead-free antiferroelectric material, silver niobate (AgNbO3)-based bulk ceramics have attracted considerable interest in the field of dielectric energy storage and are gaining emerging applications in piezoelectric actuators. Driven by the increasing demand for miniaturization, compactness, and integration of electronic devices, AgNbO3-based thin films have recently drawn growing attention. In this work, we report a novel and facile chemical solution deposition (CSD) route to synthesize phase-pure antiferroelectric AgNbO3 films on Si substrates. This was achieved by judiciously formulating chemical additives to stabilize the precursor solution and implementing a stepwise controlled thermal treatment to eliminate secondary phases. With the introduction of a buffer layer between the AgNbO3 film and the substrate, the leakage current was significantly suppressed, resulting in well-defined double hysteresis loops. Moreover, doping with a ferroelectrically active element induced an antiferroelectric-to-ferroelectric transition, which doubled the piezoelectric coefficient as measured by a laser Doppler vibrometer. These findings highlight the promise of silver niobate-based films as candidates for lead-free piezoelectric applications.
CK-2:L13 Enhancement of the Electroacoustic Device Performance of PMN-PZT Piezoceramics through Chemical Modification and Texture Development
M. KERVANCI1,2, B. DAĞAŞAN1,2, E. ERSOY1,2, M.Y. SEYITSOY2, M. BOZ1,2, A. BERKSOY YAVUZ3, S. ALKOY1,2, 1STEM Sensor Technologies and Electronic Materials Ltd, Kocaeli, Turkey; 2Dept. of Materials Sci. & Eng., Gebze Technical University, Kocaeli, Turkey; 3Dept. of Materials Sci. & Nanotechnology Eng., Istanbul Gedik University, Kartal, Istanbul
Electroacoustic transducers are electromechanical devices that can convert electrical energy into acoustical energy or vice versa. In this study, piezoceramics with 0.40Pb(Mg1/3Nb2/3)O3-0.25PbZrO3-0.35PbTiO3 (PMN-PZT) composition were chemically modified with Sm doping to enhance the soft piezoelectric character for passive sensing applications and with Mn doping to enhance the hard piezoelectric character for active drive conditions. Additionally, the PMN-PZT piezoceramics were prepared with crystallographic texture through Templated Grain Growth method to obtain anisotropic electromechanical characteristics. Transducers in 1-3 piezocomposite form, as well as in spherical or cylindrical thin shell forms have been fabricated and their electroacoustic performance have been compared with that of the undoped, randomly oriented PMN-PZT ceramics with equiaxial grains. Electrical characterization indicated an approximately 3-fold increase in the piezoelectric d33 coefficient with Sm doping and texture development, whereas Mn doping led to a 5-fold increase in mechanical quality factor. Electroacoustic measurements revealed a more stable receive voltage sensitivity performance and a 3 dB higher transmit voltage response in doped and textured ceramic with a wider -3dB bandwidth.
CK-2:IL14 From Processing to Performance: Unlocking the Potential of Lead-Free Piezoelectric Ceramics via Advanced Sintering
P.M. VILARINHO, Department of Materials and Ceramic Engineering, CICECO-Aveiro Institute of Materials, University of Aveiro, Aveiro, Portugal
Alternative sintering methods offer more efficient, environmentally friendly, and precise ways to produce high-performance ceramics by overcoming the inherent drawbacks of traditional processing techniques. Our research focuses on developing advanced sintering techniques like Ultrafast High-Temperature Sintering (UHS), Flash Sintering (FS), and Spark Plasma Texturing (SPT) for lead-free piezoelectrics, namely potassium sodium niobate (KNN) ceramics. These methods address the limitations of conventional sintering, such as high temperatures and alkali volatilization. UHS produces dense KNN (91%) with fine grain sizes (<2 µm) in short times (≤90 s), minimizing volatile loss and yielding good dielectric, piezoelectric (~80 pC/N d33), and ferroelectric properties, often requiring post-annealing for stability. Flash Sintering densifies KNN at low temperatures (below 350ºC) via surface melting and viscous flow at particle contacts, driven by localized Joule heating. An isothermal hold at 900°C before flash sintering improves density up to 95%, and reducing atmospheres can lower the flash temperature to below 320°C. While flash sintering induces compressive stresses, it results in high-performance KNN (21 μC/cm2 Pr, 117 pC/N d33) comparable to conventionally sintered materials, with electrical properties restored by post-annealing. Spark Plasma Texturing yields highly dense KNN (98.0%) with a homogeneous microstructure and enhanced elastic moduli (Bulk modulus K = 120.3 GPa), demonstrating its ability to improve electromechanical properties. These studies establish FS, UHS, and SPS/SPT as effective methods for fabricating high-performance lead-free KNN ceramics by precisely controlling densification, microstructure, and properties.
CK-2:IL15 Hybrid Improper Ferroelectricity in La2SrSc2O7-based Ceramics
XIAOQIANG LIU, ZHE GUO, YULU WEI, XIANGMING CHEN, School of Materials Science and Engineering, Zhejiang University, Hangzhou, China
Hybrid Improper Ferroelectrics (HIFs) have attracted considerable attention due to their potential for realizing room temperature multiferroicity with strong magnetoelectric coupling. HIFs exhibit a unique ferroelectric polarization induced by a complex distortion pattern involving two oxygen octahedral tilting modes. These materials are expected to be prevalent in perovskite and layered perovskite structures, as the ubiquitous distortions of oxygen octahedra occur in perovskite-related compounds. Very recently, the HIF has been discovered in A-site cation disorder La2SrSc2O7 ceramic with double-layered Ruddlesden-Popper structure, indicating the possibility of creating single-phase multiferroic in these materials since the Sc3+ can be readily replaced by the magnetic ions, such as, Fe3+. In the present work, single phase La2Sr(Sc1-xFex)2O7 ceramics were prepared, and the room-temperature ferroelectric properties have been investigated. The linear relationship between the Curie temperature and the content of Fe3+ cations has been found. Moreover, the room-temperature ferroelectricity is also observed in Ln2SrSc2O7 (Ln = Nd, Sm) ceramics, and the phase transition is studied by the In-situ X-ray diffraction.
CK-2:L16 Antiferroelectric Ceramics for Piezocatalysis
W. AMDOUNI1, A. ABASS SHAH2, M. OTONIČAR2, B. DKHIL1, 1Université Paris-Saclay, CentraleSupélec, UMR CNRS 8580, Laboratoire Structures, Propriétés et Modélisation des Solides, Gif-Sur-Yvette, France; 2Jožef Stefan Institute, Ljubljana, Slovenia
Piezocatalysis, in which ferroelectrics and piezoelectrics are generally used, is an emerging means of tackling the energy crisis and protecting the environment.[1] To strongly favor the piezocatalysis process, by selecting Sm-substituted BiFeO3 materials, our group has very recently, demonstrated an original approach consisting in using antiferroelectrics, which although not piezoelectric, counter-intuitively exhibit ultrahigh piezodegradation efficiencies for several pollutants reaching up to 100% in 30 min under ultrasonic stimulus. We have also demonstrated that beyond piezodegradation of pollutants, antiferroelectric materials are also good candidates for the production of H2O2 from water.[2] Here, despite the fact that the high catalytic efficiency is mostly achieved with nanoparticles due to high-surface to volume ratio, we show for the first time that NaNbO3-based ceramics display as well significantly greater efficiencies than previously reported ferroelectric and piezoelectric systems. These findings provide a new avenue for designing future antiferroelectric piezocatalysts with high performance for applications that include depollution, production of chemicals or biomedical technologies.
[1] W. Amdouni et al., Adv. Mater. 2023; [2] W.Amdouni et al., Nature, Submitted.
CK-2:L17 Enhanced Energy Storage in Lead-Free BaTiO3–Bi(Mg1/2Ti1/2)O3 Relaxor Ferroelectric Ceramics via Nanoscale Polarization Mismatch and Reconstruction
S. SAHU, P. DOBBIDI, Department of Physics, Indian Institute of Technology Guwahati, Assam, India; D. KALYANI, Department of Zoology, Adikavi Nannaya University, Rajamahendravaram, India
Progress in energy storage ceramics has attracted significant attention due to their environmentally friendly nature and superior ferroelectric/dielectric performance. In this study, lead-free (1−x)BaTiO3–xBi(Mg1/2Ti1/2)O3 (x = 0.05–0.20) relaxor ferroelectric ceramics are synthesized and identified as promising candidates for high-performance energy storage applications. Herein, an effective strategy is proposed to achieve enhanced energy storage performance through nanoscale polarization mismatch and reconstruction, realized by developing solid solutions involving A-site and B-site coupled ferroelectrics. Temperature-dependent dielectric measurements (133–473 K, 1–100 MHz) revealed dieletric value increased from 1094.54 (BT–BMT1) to 1362.28 (BT–BMT3) at 1 MHz, then decreased to 951.44 (BT–BMT4), with the transition temperature shifting from 393 K to 413 K and slightly reducing to 408 K for higher BMT content. The BT–BMT3 showed the best performance, achieving a maximum dielectric constant of 1362.28 at 1 MHz, a transition temperature (413 K), low dielectric loss (0.09), and minimal conductivity. Notably, an ultrahigh recoverable energy density (Wrec) of 2.52 J/cm3 and an efficiency (η) of 71% are obtained, confirming BT–BMT3 as a promising lead-free energy storage systems.
CK-2:L18 Role of Incommensurate Modulation in Tetragonal Tungsten Bronze Ferroelectrics
YI BANG OU, XIAO LI ZHU, JIA WEN SONG, XIANG MING CHEN, School of Materials Science and Engineering, Zhejiang University, Hangzhou, China
The role of incommensurate (IC) modulation in evolution of the pinched polarization-electric field (P-E) hysteresis loops has been investigated and discussed based on the structure and polarization evolution in Ba4(Sm1-xLax)2Ti4Nb6O30 tetragonal tungsten bronzes. Relaxor behavior in the La rich compound is accompanied by the IC modulation structure. Introduction of smaller Sm in the system increases the driving force for the transition from an IC modulation structure to a commensurate superstructure, which coupled with the ferroelectric transition in the middle composition with x = 0.5. In the Sm rich compounds, IC modulation structure reappears as a metastable state to balance the structural instability caused by the too small average ionic radius of the rare-earth ion, meanwhile the field-induced transition from IC modulation structure to commensurate superstructure is confirmed by the selected area electron diffraction (SAED) using an in-situ bias technique as the structural origin for the pinched P-E loops. A phase diagram has been established by combining the ferroelectric phase transition and the modulation structure transition, and a new region with both very small A-site size (A1+A2)/2 and A1-site tolerance factor (tA1) related to the ferroelectric compounds with pinched P-E loops (pinched FE) were added into the previously reported crystal-chemical framework. The present work expands the composition−structure−properties relationships in tungsten bronze ferroelectrics by including the recently reported “pinched FE”, and meanwhile extends the composition manipulation ranges from crossover between relaxor and normal ferroelectrics to ferroelectrics with pinched P-E loops.
CK-2:L19 Textured KNN Based Lead Free Piezoceramics via Templated Grain Growth
N. YÜRÜK1,2, E. SUVACI1,2, 1Eskisehir Technical University, Department of Materials Science and Engineering, Eskisehir, Türkiye; 2Entekno Industrial, Technological and Nano Materials Corp, Eskişehir, Turkey
Lead-based piezoceramics are widely used in transducers, which are the main components of ultrasonic and sensor technologies. The primary reason is that the electrical properties of currently produced lead-free materials remain significantly lower than those of lead-based ceramics. However, the release of lead into the environment continues to cause increasing harm K₀.₅Na₀.₅NbO₃ (KNN) have gained attention, particularly through studies involving Li, Sb, and Ta dopants, as well as textured microstructures produced using NaNbO₃ plate templates. These developments have led to reported d₃₃ values as high as 400–700 pC/N. In this study, the effect of Li addition on the electrical properties of KNN-based ceramics was investigated using uniaxial pressing and <00l>-oriented NaNbO₃ plate templates. It has been shown that textured microstructures can be achieved via Templated Grain Growth process. In the presentation, effects of template content, shaping technique, shaping conditions and sintering conditions on texture development and piezoelectric coefficients (d₃₃) will be discussed.
CK-2:L21 Macroscopic Tin Monochalcogenide Van der Waals Ferroics: Growth, Domain Structures, Curie Temperatures and Lateral Heterostructures
E. SUTTER, Department of Mechanical & Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA; P. SUTTER, Department of Electrical & Computer Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA
Layered (van der Waals) crystals promise new families of ferroics with switchable electric polarization, strain, or magnetic order. So far, synthesis was limited to small (few microns) crystals, where proximity to edges affects domain patterns and limits the achievable device architectures. Here, we report the realization of in-plane ferroelectric/elastic few-layer monochalcogenide (SnS, SnSe) crystals whose dimensions exceed the state of the art by one order of magnitude. Such large crystals allow investigating ferroic domains unaffected by finite size effects. Analysis by in-situ electron microscopy and diffraction shows two distinct domain types, provides measurements of Curie temperatures, and sheds light on symmetry breaking and the transition between the polar and the symmetric (high-T) phase.1,2 Finally, we demonstrate the integration of such monochalcogenides into heterostructures,3 where domain patterns and the low-symmetry (polar) structure can be templated across interfaces. The combined results demonstrate industrial-scale van der Waals ferroics and heterostructures presenting extraordinary opportunities for manipulating ferroelectric order.
1. J. Am. Chem. Soc. 146, 31961 (2024); 2. Proc. Nat. Acad. Sci. 122, e2501509122 (2025); 3. ACS Nano 18, 30829 (2024).
CK-3 Thermoelectric ceramics
CK-3:IL22 Bond Covalency and Carrier-Phonon Coupling in Oxyselenides
JIHUI YANG, Department of Materials Science and Engineering, University of Washington, Seattle, WA, USA
BiCuSeO oxyselenides are attractive thermoelectric materials for intermediate temperatures, owing to their ultralow lattice thermal conductivity and large Seebeck coefficient. Their thermoelectric performance, however, is constrained by intrinsically low carrier mobility. In this talk, we demonstrate that strengthening chemical bond covalency reduces the effective mass and weakens carrier–phonon coupling, thereby enhancing carrier mobility. Te-doping further improves mobility while maintaining electrical conductivity and sustaining high power factors, even at lower carrier concentrations. At the same time, hierarchical structural features—including dual point defects, nanoinclusions, and grain boundaries—formed during nonequilibrium self-propagating high-temperature synthesis (SHS), drive the lattice thermal conductivity toward the amorphous limit. Altogether, our findings show that tuning chemical bonding to mitigate carrier–phonon interactions provides a promising pathway to further improve the thermoelectric performance of BiCuSeO.
CK-3:IL23 WOx/CuOx Heterojunction Optoelectronic Memristive Synapses for Face Recognition Application
TSEUNG-YUEN TSENG, Institute of Electronics, National Yang Ming Chiao Tung University, Taiwan
The impact of annealing on the performance of memristive devices fabricated by WOx/CuOx p-n films sandwiched between ITO electrodes is investigated. The device has low SET and RESET voltages, stable and robust AC endurance of up to 106 cycles, and can retain the states for more than 104 s. The device demonstrates synaptic capabilities by emulating neural functions under both electrical and light stimuli. The behaviors including long-term potentiation/depression, paired-pulse facilitation, spike-timing-dependent plasticity, fully tunable relaxation time of short-term memory, mimicking the temporal dynamics of the biological neuron are declared. A convolutional neural network operation is conducted by exploiting the synaptic functions of the device. The high accuracy of 96.67% with high noise tolerance (close to an ideal synapse) can be achieved. Material analyses are conducted and switching/synaptic mechanisms are proposed to explain such phenomena.
CK-3:IL24 Controlling the Electrical Properties of Perovskites Using Defect Chemistry
D.C. SINCLAIR, University of Sheffield, School of Chemical, Materials and Biological Engineering, Sheffield, UK
Alkaline earth titanate (Ba,Sr)TiO3 (BST) and alkali niobate (Na,K)NbO3 (KNN) perovskites exhibit a diversity of electrical properties based on various donor and/or acceptor dopant mechanisms. Here we survey the influence of A-site donor doping mechanisms via electronic and/or ionic compensation mechanisms to modify the electrical properties of BST and NaNbO3 (NN). The dominant doping mechanisms are different in BST and NN and this has implications for applications as either thermoelectrics, high energy density dielectrics or mixed conducting electrode materials. It also has consequences for further modification of their electrical properties when they are processed in reducing atmospheres to induce oxygen-loss and promote high levels of electronic conduction via mixed Ti3+/Ti4+ and Nb4+/Nb5+ oxidation states.
CK-3:IL25 Half-Heusler Thermoelectrics with Tunable Vacancy Orders
TIEJUN ZHU, State Key Laboratory of Silicon and Advanced Semiconductor Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, P.R. China
Semiconducting half-Heusler compounds with the valence electron count of 18 have been identified as a class of promising high-temperature thermoelectric materials. Recently, nominal 19-electron half-Heusler compounds, possessing massive intrinsic vacancies at the cation site and intrinsically low lattice thermal conductivity, have gained reacquaintance and popularity due to their unexpected high thermoelectric performance and fascinating defective structure. In this talk, we introduce the current progress of half-Heusler thermoelectric materials, the discovery and challenge of new cation-deficent half-Heusler compounds with the vacancy-related short-range order, and the transition between the short range order and long range order. The relationship between the vacancy order and physical properties are established and explained.
CK-3:L25b Ductile Semiconductors and their Thermoelectric Properties
XUN SHI, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China
We report the recently discovered ductile inorganic semiconductor materials such as Ag2S and its alloys, and defective Bi2Te3-based materials. They are typical semiconductors with excellent thermoelectric performance. At the same time, they are highly plastic, which are similar with the mechanical properties of metals. Furthermore, upon compositional optimization, these ductile materials can reach a delicate balance between high carrier mobility, power factor, a figure of merit and good mechanical plasticity. The good ductile thermoelectric materials open a new avenue for the fabrication of flexible and other new thermoelectric devices. These results promised an emerging paradigm and market of thermoelectric materials and devices.
CK-4 Caloric ceramics
CK-4:IL26 Development of Electrocaloric Multilayer Capacitors for Energy-efficient Cooling Applications
SAKYO HIROSE, Murata Manufacturing Co., Ltd., Nagaokakyo, Kyoto, Japan
The electrocaloric (EC) effect, a reversible thermal change induced by an electric field, occurs in ferroelectric and antiferroelectric materials, and it has gained considerable attention as a promising basis for next-generation solid-state cooling. Due to the urgent need for environmentally friendly and energy-efficient cooling solutions, substantial research efforts have focused on EC materials and cooling prototypes. At Murata manufacturing, we utilized our well-established multilayer capacitor (MLC) technology—originally developed for capacitor and piezoelectric applications—to design and fabricate EC MLCs with extremely high breakdown strength and large EC responses near room temperature. In the MLCs of highly ordered PbSc0.5Ta0.5O3 (PST), we achieved an adiabatic temperature change of approximately 5 K around room temperature and supplied MLCs of PST for the development of regenerative EC cooling systems. Recently, we have expanded our work to novel solid-solution compositions, PST-PbMg0.5W0.5O3, to improve performance and extend the operating temperature window. In my presentation, I will highlight recent progress in EC materials and MLC device development and outline pathways toward energy-efficient cooling technologies.
CK-4:IL27 Electrocaloric Cooling Efficiency: Comparative Insights on P(VDF-TrFE-CFE) Polymer and BSTM Ceramics
M. ALMANZA1,2, S. SADHUKHAN1, N. ZEGGAI1, B. DKHIL2, M. LOBUE1, 1Université Paris-Saclay, ENS Paris-Saclay, CNRS, SATIE, Gif-sur-Yvette, France; 2Université Paris-Saclay, CentraleSupélec, CNRS, Laboratoire SPMS, Gif-sur-Yvette, France
In response to the increasing demand for efficient and compact refrigeration and energy conversion devices, research has focused on identifying optimal electrocaloric (EC) materials among ferroelectric ceramics and polymers. This study investigates the EC properties of the Poly [(Vinylidene Fluoride)0.664-(Trifluoroethylene)0.245-(Chlorofluoroethylene)0.91] terpolymer and multi-layer ceramic Ba0.6Sr0.4Ti0.998Mn0.002O3 (BSTM) ceramics, comparing various parameters to assess their suitability for electrocaloric cooling. Adiabatic temperature change (ΔTad) are measured with direct method and with electric field compatible with long-term operation. The loss in ferroelectric hysteresis is observed to be much lower in BSTM than in PVDF Terpolymer. Hence, the resulting Cooling efficiency, computed over a thermodynamic cycle mimicking Carnot efficiency, reveals that the PVDF Terpolymer achieves a relative cooling efficiency lower than the BSTM ceramics. The PVDF Terpolymer outperforms BSTM ceramics in terms of adiabatic temperature change but not in terms of expected cooling efficiency. Through our methodology it reveals that both BSTM ceramics and PVDF terpolymers emerge as promising electrocaloric materials for solid-state cooling but they have complementary strengths. We would also like to thank Murata, Piezotech Arkema for their samples.
CK-5 Semiconducting and fast ion-conducting ceramics
CK-5:IL28 Long Term Materials Performance in High Temperature Electrochemical Systems
P. SINGH, P.K. DUBEY, University of Connecticut, Storrs, CT, USA; T. SUZUKI, Precision Combustion Inc., New Haven, CT, USA
Status of oxygen ion and proton conducting high temperature solid state electrochemical technologies for power generation and hydrogen production are reviewed. Recent advances and research trends in electrochemical cell and stack materials selection and fabrication processes are discussed. Experimental observations on long-term electrochemical performance and structural changes are examined and presented. Thermochemical and electrochemical reactions and processes responsible for the above degradation along with related degradation mechanisms are discussed. Surface, interface and bulk degradation in electrochemically active and in-active cell / stack components are examined and their role on irreversible changes in the ohmic and non-ohmic polarization losses are discussed. This presentation will focus on electrode and electrolyte (doped perovskites/ fluorites) structural and chemical changes during exposure to humid atmospheres containing trace gaseous impurities (at ppm/ppb levels). Processes related to dopant exsolution, trace contaminant interaction and electrode poisoning under anodic and cathodic conditions will be described. Accelerated metal corrosion under H2-H2O redox and bi-polar exposure conditions will be discussed with emphasis on the breakdown of passivation and formation of localized non-protective surface scale. Phenomena related to Hydrogen permeation in metal, hydrogen interaction with metal impurities and porosity formation will be discussed.
CK-5:IL29 3D Printed BaTiO3-based Semiconducting Ceramics with High PTC Effect
WEN ZHENG, XI CHEN, BINGXIAO XUE, TIANWEN DONG, KAIXIN CHEN, WEI LUO, QIUYUN FU, School of Integrated Circuit, Engineering Research Center for Functional Ceramics of Ministry of Education, Huazhong University of Science and Technology, Wuhan, Hubei, P.R. China
The realization of complex structures using emerging vat photopolymerization (VPP) technology is limited by the poor curing properties of leaded PTC ceramic slurry. Herein, this study presents an innovative approach of combining VPP technology with vacuum infiltration (VI) process for fabricating high-performance PTC ceramics. Notably, the introduction of soluble starch significantly enhances the curing depth and printability of PTC ceramic slurry. Meanwhile, silica nanoparticles in silica sols are infiltrated into 3D printed green bodies to improve the electrical properties of PTC ceramics. At optimal soluble starch content and silica concentration, a lower room temperature resistivity (ρ=207 Ω·cm) and a higher temperature coefficient of resistance (α0-15=25.14 %/℃) are obtained in printed PTC ceramics compared to dry pressed PTC ceramics (ρ=301 Ω·cm, α0-15=19.32 %/℃). Therefore, this work provides a novel technological strategy for fabricating high-performance PTC ceramics with desirable structures and can promote the wide application of PTC heating elements.
CK-5:IL30 Progress in Protonic Ceramic Electrolysis Cells (PCECs)
S. RICOTE, Y. SHIN, R.J. KEE, Colorado School of Mines, Golden, CO, USA
Protonic Ceramic Electrolysis Cells (PCECs) are an emerging technology for hydrogen production that operates efficiently within the intermediate temperature range of 400–600 °C. With growing scientific interest and promising electrochemical performance, PCECs hold potential. However, critical challenges still hinder their path to commercialization, namely, low Faradaic efficiency under certain conditions, demanding requirements for steam electrode (positrode) materials, and the need for scalable, cost-effective manufacturing processes. Following an introduction to protonic ceramics and a review of recent advancements in PCECs, this presentation will explore strategies for developing advanced positrode materials using composite designs. It will also examine the dependence of Faradaic efficiency on key operating conditions, such as temperature and gas composition. Finally, the talk will propose methods to improve Faradaic efficiency and introduce a measurement protocol designed to reduce experimental uncertainty.
CK-5:L31 High Temperature Dielectric Properties of Graphitic-carbon Coated 8YSZ Nanoplatelets
A. MISHRA, S. BISWAS, Dept. of Physics, The LNM Institute of Information Technology, Jaipur, Rajasthan, India
High temperature dielectric properties of graphitic-carbon coated 8.0 mole% Y2O3-stabilized ZrO2 (8YSZ) nanoparticles (NPs) were studied in ambient air. The platelet-shaped NPs were synthesized by a simple chemical process. The process permits fine-tuning of the morphology of the NPs along with the formation of an in situ grown surface layer of graphitic-carbon. The morphology and surface structure of the 8YSZ NPs were studied by high resolution transmission electron microscope and Raman spectroscopy. The graphitic-carbon layer plays a critical role in controlling the dielectric properties of the 8YSZ nanoplatelets. In this paper, we report on the high temperature dielectric characteristics of the 8YSZ nanoplatelets in correlation with their surface structure.
CK-1:IL01 Ordered Domain Engineering of Ba-based Complex Perovskite Ceramics
XIAO LI ZHU, XIANG MING CHEN, School of Materials Science and Engineering, Zhejiang University, Hangzhou, China
It is an important subject to improve the temperature coefficient of resonant frequency (τf) and thermal conductivity (κ) of microwave dielectric ceramics without reducing the Q×f value. Ordered domain engineering was applied to realize the previous objectives in a series of Ba-based complex perovskite ceramics. With the increasing ordering degree, collaborative optimization of microwave dielectric properties was obtained. The noticeable ordered domain structure with large ordered domains (∼100 nm) and low-energy domain boundaries was revealed in materials with excellent performance. The consequent weakened phonon scattering rises the thermal conductivity. The increased bond covalency and oxygen distortion in ceramics with higher ordering degree were suggested as a cause of enlarged bandgap, which enhanced the dielectric strength. The reduced τf is dominated by the less “rattling” space of the cations in the ordered state by inducing more positive τε. The reduced τf, optimized thermal conductivity, and Q×f value in the present work indicate that the ordered domain engineering could open up a new direction for the optimization of microwave dielectric ceramics.
CK-1:IL02 Controlled Dielectric Properties of 3D-Printed Gyroid Ceramics for Enhanced Dielectric Resonator Antenna Performance
R. BENZERGA1, T. LAVIE1, M. JULIAN1, L. LE GENDRE1, A. SHARAIHA1, F. CHEVIRÉ2, C. LE PAVEN1, 1IETR, Institute of Electronics and Telecommunications of Rennes, University of Rennes, France; 2ISCR, Institute of Chemical Sciences of Rennes, University of Rennes, France
The rapid evolution of wireless telecommunications has intensified the search for advanced dielectric materials and novel manufacturing strategies. In this context, our research explores the dielectric properties of ceramics shaped into gyroid structures using additive manufacturing and commercially available alumina and zirconia materials. By controlling the gyroid geometry, we achieved significant adjustment of the resonators’ effective permittivity from the intrinsic values of the bulk ceramics (32.7 for zirconia and 9.4 for alumina) down to values approaching that of air (1). Experimental measurements closely matched theoretical predictions based on the Maxwell-Garnett Approximation as the proportion of air within the structure increased. To demonstrate the potential of this approach, two dielectric resonator antenna prototypes are fabricated: a conventional bulk alumina antenna and a zirconia gyroid antenna presenting the same effective permittivity. Both prototypes exhibited similar resonance frequencies, confirming the accuracy of our permittivity control, as measured by the resonant cavity method in the gigahertz range. The gyroid antenna achieved a 50% reduction in weight, a key advantage for satellite communication applications. Our accessible measurement techniques provide clear design guidelines, reproducible production of lightweight, high-resolution ceramic components with tailored dielectric properties, thereby broadening the material landscape for next-generation telecommunications devices.
CK-1:IL03 Integration of Functional Materials in LTCC and SiCer Multilayer Substrate Modules
J. TÖPFER1, M. HEIDENREICH1, T. SCHULZ1, B. CAPRARO2, 1Ernst-Abbe-Hochschule Jena, Jena, Germany; 2Fraunhofer IKTS, Hermsdorf, Germany
We have studied the integration of functional materials into LTCC multilayers architectures. We will report on SiCer composite substrates which are fabricated by combining Si wafers and LTCC multilayer systems through cofiring at 900°C, wafer processing, and assembly of the complete module. SiCer composite substrates allow fabrication of MEMS, sensor- and communication modules. A specific LTCC tape material BCT was developed for shrinkage matching. Examples for the integration of functional materials into the LTCC multilayer system include ferrites for integrated transformers, dielectrics for integrated capacitors, and NTC spinels as temperature sensors. We also report on LTCC multilayer modules with integrated magnetic microwave components for satellite communication systems in the Ka-band (26-40 GHz). We studied Sc-substituted M-type ferrites BaMexFe12-xO19. Static magnetic measurements show that both the saturation magnetization and coercivity decrease with x, indicating a reduction of the anisotropy field and ferromagnetic resonance frequency (FMR). The FMR for ferrites with x = 0.5 is at 30 GHz allowing such materials to be used for Kq-band circulator applications. Integration of anisotropic ferrites into LTCC multilayer modules was realized as bulk drop-in components into LTCC cavities. Alternatively, anisotropic ferrite films are obtained by screen-printing or tape casting, subsequent drying in magnetic field and cofiring. Such oriented self-biasing ferrite layers are used in LTCC multilayer microwave components.
CK-1:IL04 Development of High Dielectric Ceramic Filled PTFE Substrates and Design of Compact MIMO Antenna for Sub-6 GHz Band Applications
R. RATHEESH1,2, CH MADHURYA1, J. MANIKANTA1, S. AKSHDEEP1, 1Centre for Materials for Electronics Technology (C-MET), Ministry of Electronics & Information Technology, Government of India, IDA Phase III, Hyderabad, Telangana, India; 2Centre for Materials for Electronics Technology (C-MET), Ministry of Electronics & Information Technology, Government of India, Panchawadi, Pune, Maharashtra, India
Copper cladded PTFE/ceramic laminates are the prime choice for high frequency communication applications considering their tailorable dielectric constant, low dielectric loss, high thermal resistance and excellent thermal stability for applications such as telecommunication, automotive, aerospace, defense etc. Miniaturization is another key requirement in these sectors which positioning these laminates as critical enabler for innovation. In the present work, high dielectric ( r=13.5) and low loss tangent ( tan =0.002) PTFE/ceramic laminates have been developed through a patented SMECH process comprising of Sigma Mixing, Extrusion, Calendering and Hot Pressing. Vaccum lamination technique has been used for cladding 35 thick oxygen free copper foil on to plasma etched PTFE/cearmic lamiantes. X-band waveguide cavity perturbation technique is used for precisely measuring the dielectric properties of the fabricated composite laminates. A compact multiple input and multiple output (MIMO) antenna is designed using High Frequency Structure Simulator (HFSS) for 5G communication applications. The proposed design consists of two element array-based antenna system with each element is having 1x3 array with coaxial feed. Radiating patch array has two step rectangular slots on either side of the patch. Two step rectangular stubs are added parallel to the edge of the patch on both sides. The stubs and slots in the patch increase the bandwidth of the designed antenna. Isolation of the MIMO antenna is improved from -10 dB to -35 dB at center frequency and -16 dB in the frequency band by defected ground structure. The fabricated antenna resonates with an impedance band width from 3520 MHz to 3825 MHz and having 15 dB isolation. Antenna has a high gain of 7.6 dBi with good envelope correlation factor. Measured results are in good agreement with simulations studies.
CK-1:IL05 P-V-L Theory and First Principle Density of States Calculation for Chemical Bond Evaluation of Microwave Dielectric Ceramics
HONGYU YANG, HONGCHENG YANG, ENZHU LI, School of Integrated Circuit Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
The first principle calculation, recognized for its reliability in elucidating the intrinsic correlations between the structure and properties of microwave dielectric ceramics, is often hindered in practical applications due to its inherent complexity. In response, the P-V-L theory, a simplification of the complex chemical bond theory, has emerged as an alternative. This theory establishes a general relationship between lattice vibration modes/chemical bonds and the dielectric constant and loss, offering a robust theoretical framework to uncover the intrinsic microwave dielectric response mechanisms of these ceramics. Nonetheless, the accuracy of chemical bond bonding outcomes within the P-V-L theory is pivotal to the reliable computation of other chemical bond property parameters. Consequently, the validation of chemical bond bonding results in microwave dielectric ceramics is essential to ensure the precise correlation between chemical bond property parameters and microwave dielectric properties. First principle density of state calculations and P-V-L theoretical chemistry bond calculations have been conducted on microwave dielectric ceramic systems that incorporate rare earth ions, exhibiting diverse crystal structures, complexities, and dielectric properties. The prospective application of these two methodologies in evaluating chemical bond bonding results across other microwave dielectric ceramic systems is anticipated, laying a foundation for comprehending the interplay between chemical bond property parameters and microwave dielectric properties
CK-1:L06 Numerical Simulations of AlGaN/GaN-FP-HEMTs Performance for High Frequency Applications
M. KADDECHE1, Z. EDDINE KADDECHE2, 1Department of Electronics and communivations,Faculty of Science and Technology, Djilali Bounaama University of Khemis Miliana, Ain Defla, Algeria; 2Faculty of E.A.S, Kütahya Dumlupınar University, Kutahya, Turkey
The excellent microwave power performance demonstrated in AlGaN/GaN HEMTs (high-electron mobility transistors) results from the combination of high current density with high voltage operation [1], which benefits from the high sheet charge density in these hetero-structures (1013 cm-2), the high carrier mobility (1500 cm2/Vs) and saturation velocity (1.5 × 107 cm/s) in the channel and the high breakdown voltage inherent in the GaN material. However, their reliability still limits their applications in today’s electronic systems. The newly developed field-plated AlGaN/GaN high electron mobility transistors show improved performance due to the electric field reduction in the device channel and surface modification [2]. We report on two dimensional numerical simulations of gate-recessed and field-plated AlGaN/GaN HEMTs where all the important device parameters have been defined, the insulator thickness under the field plate is also an important design parameter to attain higher breakdown voltage, GaN-based FP-HEMTs technology still presents great potential to get good microwave power at high frequency. To our knowledge, this performance constitutes state of the art at 40 GHz for AlGaN/GaN HEMTs.
CK-1:L07 AI-Driven Prediction Model for Material Properties of Multilayer Ceramic Capacitors
HYEJEONG SONG1, MINTAEK SEO1,2, HYUNSEOK KO1, 1Convergence Research Division, Korea Institute of Ceramic Engineering and Technology, Jinju, Republic of Korea; 2Department of Materials Engineering, Gyeongsang National University, Jinju, Republic of Korea
Multilayer ceramic capacitors (MLCCs) are key components for next-generation electronics, but their optimization through traditional trial-and-error is inefficient. To accelerate development, a predictive design framework is essential for achieving high permittivity, low dielectric loss, and long-term stability. We have developed a novel artificial intelligence (AI) model to predict dielectric constant, dielectric loss, and material density based on chemical composition and processing conditions. The core innovation of our approach is a "simulation-informed" methodology; the model integrates high-fidelity theoretical properties derived from first-principles (DFT) calculations with experimental data. This unique fusion bridges the gap between atomic-scale physics and macroscopic performance, enabling more accurate and physically grounded predictions. The model automatically associates theoretical property data with input compositions, enhancing both training and prediction. We expect this AI-driven strategy to create a highly efficient design loop, significantly reducing experimental workload, shortening development time, and lowering costs for advanced MLCCs.
CK-1:L08 Influence of Gamma Irradiation on the Structure and Dynamics of the Crystal Lattice of Solid Solutions of Ferrites Co1-xZnxFe2O4 (x = 0, 0.25, 0.5, 0.75, 1)
H. RYMSKI, Scientific and Practical Center for Materials Science of the National Academy of Sciences of Belarus, Minsk, Belarus; M. BUNEVICH, Belarusian State University of Informatics and Radioelectronics, Minsk, Belarus; I. LAGUTSKIY, ATOMTEX SPE, Minsk, Belarus
Solid solutions of spinel ferrites Co₁₋ₓZnₓFe₂O₄ (x = 0, 0.25, 0.5, 0.75, 1) were synthesized via a modified sol–gel route. X-ray diffraction, Raman spectroscopy, and dielectric spectroscopy were employed to assess the impact of γ-irradiation at 2.5, 5, and 10 kGy on structure and lattice dynamics. The cubic lattice parameter increases from a = 8.3768 Å in CoFe₂O₄ to a = 8.4297 Å in ZnFe₂O₄, consistent with a transition from an inverse (CoFe₂O₄) to a normal (ZnFe₂O₄) spinel. The average crystallite size and microstrain decrease from D = 55.952 nm and ε = 0.988 for CoFe₂O₄ to D = 25.002 nm and ε = 0.255 for ZnFe₂O₄. Within this dose range, lattice metrics change only weakly under ionizing γ-radiation; nevertheless, Raman signatures confirm the formation of radiation-induced defects and a redistribution of cations between tetrahedral (A) and octahedral (B) sites in the spinel lattice.
CK-2 Ferroelectric, piezoelectric, pyroelectric, and ferroelastic ceramics
CK-2:IL09 Solid-state Formation Reactions and Dopant Incorporation in the Complex Perovskite Piezoceramic (Ba,Ca)(Zr,Ti)O3
J. KORUZA1, A.M. PAULIK1, A.S. STECHER1, O. CLEMENS2, M. WIDENMEYER3, 1Institute for Chemistry and Technology of Materials, Graz University of Technology, Graz, Austria; 2Institute for Materials Science, Chemical Material Synthesis Group, University of Stuttgart, Stuttgart, Germany; 3Department of Materials and Earth Sciences, Technical University of Darmstadt, Darmstadt, Germany
Emerging electroceramics with complex multi-ionic compositions increasingly challenge the boundaries of solid-state processing methods, often resulting in chemical heterogeneities, secondary phase formation, and problems with repeatability. This is particularly evident in the field of lead-free piezoceramics, where compositions with five or more metallic cations are often considered in order to improve functional properties through phase boundary and defect engineering [1]. Here, we present a study of the formation reactions and microstructure evolution in the lead-free piezoceramic (Ba,Ca)(Zr,Ti)O3 system, using various solid-state processing routes. We report the finding of new intermediate oxycarbonate phases and demonstrate approaches for secondary phase removal and improved material homogeneity [2]. Moreover, we investigated the role of additional acceptor and donor ions on the microstructure formation and functional properties, paving the way for new doping strategies using Fermi level engineering [3].
[1] Acosta et al., Appl Phys Rev 4, 041305 (2017); [2] Paulik et al., J Eur Ceram Soc 46, 117736 (2026); [3] Klein et al., J Electroceram 51, 147 (2023).
CK-2:IL10 Lead-free Piezoelectric Ceramics Based on (K,Na)NbO3: From Bulk Materials to Thin Films
JING-FENG LI, State Key Laboratory of New Ceramic Materials, School of Materials Science and Engineering, Tsinghua University, Beijing, China
Piezoelectric materials are integral to a broad spectrum of electronic devices, such as sensors, transducers, and actuators. From the standpoint of environmental sustainability, the development of high-performance lead-free piezoelectric ceramics has emerged as a critical priority. (K,Na)NbO3 (KNN) has been recognized as one of the most promising lead-free candidates, attracting extensive research attention over the past two decades. Through phase boundary engineering and multiscale structural design, the piezoelectricity of KNN-based ceramics has reached levels comparable to, and in some cases surpassing, those of conventional Pb(Zr,Ti)O3 (PZT)-based ceramics. While the majority of research has focused on enhancing the piezoelectric properties of KNN-based bulk ceramics, recent advancements have stimulated growing interest in thin films for miniaturized devices. This presentation will first review the progress in developing KNN-based ceramics with enhanced piezoelectricity and improved temperature stability. Subsequently, I will present the latest advances in KNN-based thin films exhibiting large linear piezoelectric strains at high frequencies. Finally, I will show some application examples and offer perspectives on the further development of lead-free piezoelectric ceramics.
CK-2:L11 Electric Properties of Single-crystalline Ferroelectric Oxide Thin Films Transferred onto Polymer Membranes
HIROAKI NISHIKAWA, B.O.S.T. Kindai University, Kinokawa, Japan
Since the pioneering work by Nomura et al. on transparent flexible thin-film transistors using oxide materials, research on flexible oxide devices has advanced rapidly. Most studies in this field employ polymer membranes as flexible substrates, which requires low-temperature processing due to their limited heat resistance. A common approach has been the exploration of amorphous oxide materials, which can be deposited at room temperature and exhibit properties such as high carrier mobility. This has led to significant progress in applying amorphous oxide semiconductors to various flexible devices. Conversely, traditional applications of oxide materials often rely on their ability to integrate diverse electronic functions, which requires epitaxial thin films due to their strong anisotropy. However, the high process temperatures required for epitaxial growth have thus far precluded their use with flexible polymer membranes. This underscores the need for novel processes to enable traditional oxide material applications in flexible devices. In this study, we propose a transfer process for epitaxially grown functional oxide thin films, initially deposited on suitable substrates, to flexible polymer membranes.
CK-2:L12 Synthesis and Characterization of Silver Niobate-based Thin Films
LIANG SHU, J.F. LI, Tsinghua University, Beijing, China
As a typical lead-free antiferroelectric material, silver niobate (AgNbO3)-based bulk ceramics have attracted considerable interest in the field of dielectric energy storage and are gaining emerging applications in piezoelectric actuators. Driven by the increasing demand for miniaturization, compactness, and integration of electronic devices, AgNbO3-based thin films have recently drawn growing attention. In this work, we report a novel and facile chemical solution deposition (CSD) route to synthesize phase-pure antiferroelectric AgNbO3 films on Si substrates. This was achieved by judiciously formulating chemical additives to stabilize the precursor solution and implementing a stepwise controlled thermal treatment to eliminate secondary phases. With the introduction of a buffer layer between the AgNbO3 film and the substrate, the leakage current was significantly suppressed, resulting in well-defined double hysteresis loops. Moreover, doping with a ferroelectrically active element induced an antiferroelectric-to-ferroelectric transition, which doubled the piezoelectric coefficient as measured by a laser Doppler vibrometer. These findings highlight the promise of silver niobate-based films as candidates for lead-free piezoelectric applications.
CK-2:L13 Enhancement of the Electroacoustic Device Performance of PMN-PZT Piezoceramics through Chemical Modification and Texture Development
M. KERVANCI1,2, B. DAĞAŞAN1,2, E. ERSOY1,2, M.Y. SEYITSOY2, M. BOZ1,2, A. BERKSOY YAVUZ3, S. ALKOY1,2, 1STEM Sensor Technologies and Electronic Materials Ltd, Kocaeli, Turkey; 2Dept. of Materials Sci. & Eng., Gebze Technical University, Kocaeli, Turkey; 3Dept. of Materials Sci. & Nanotechnology Eng., Istanbul Gedik University, Kartal, Istanbul
Electroacoustic transducers are electromechanical devices that can convert electrical energy into acoustical energy or vice versa. In this study, piezoceramics with 0.40Pb(Mg1/3Nb2/3)O3-0.25PbZrO3-0.35PbTiO3 (PMN-PZT) composition were chemically modified with Sm doping to enhance the soft piezoelectric character for passive sensing applications and with Mn doping to enhance the hard piezoelectric character for active drive conditions. Additionally, the PMN-PZT piezoceramics were prepared with crystallographic texture through Templated Grain Growth method to obtain anisotropic electromechanical characteristics. Transducers in 1-3 piezocomposite form, as well as in spherical or cylindrical thin shell forms have been fabricated and their electroacoustic performance have been compared with that of the undoped, randomly oriented PMN-PZT ceramics with equiaxial grains. Electrical characterization indicated an approximately 3-fold increase in the piezoelectric d33 coefficient with Sm doping and texture development, whereas Mn doping led to a 5-fold increase in mechanical quality factor. Electroacoustic measurements revealed a more stable receive voltage sensitivity performance and a 3 dB higher transmit voltage response in doped and textured ceramic with a wider -3dB bandwidth.
CK-2:IL14 From Processing to Performance: Unlocking the Potential of Lead-Free Piezoelectric Ceramics via Advanced Sintering
P.M. VILARINHO, Department of Materials and Ceramic Engineering, CICECO-Aveiro Institute of Materials, University of Aveiro, Aveiro, Portugal
Alternative sintering methods offer more efficient, environmentally friendly, and precise ways to produce high-performance ceramics by overcoming the inherent drawbacks of traditional processing techniques. Our research focuses on developing advanced sintering techniques like Ultrafast High-Temperature Sintering (UHS), Flash Sintering (FS), and Spark Plasma Texturing (SPT) for lead-free piezoelectrics, namely potassium sodium niobate (KNN) ceramics. These methods address the limitations of conventional sintering, such as high temperatures and alkali volatilization. UHS produces dense KNN (91%) with fine grain sizes (<2 µm) in short times (≤90 s), minimizing volatile loss and yielding good dielectric, piezoelectric (~80 pC/N d33), and ferroelectric properties, often requiring post-annealing for stability. Flash Sintering densifies KNN at low temperatures (below 350ºC) via surface melting and viscous flow at particle contacts, driven by localized Joule heating. An isothermal hold at 900°C before flash sintering improves density up to 95%, and reducing atmospheres can lower the flash temperature to below 320°C. While flash sintering induces compressive stresses, it results in high-performance KNN (21 μC/cm2 Pr, 117 pC/N d33) comparable to conventionally sintered materials, with electrical properties restored by post-annealing. Spark Plasma Texturing yields highly dense KNN (98.0%) with a homogeneous microstructure and enhanced elastic moduli (Bulk modulus K = 120.3 GPa), demonstrating its ability to improve electromechanical properties. These studies establish FS, UHS, and SPS/SPT as effective methods for fabricating high-performance lead-free KNN ceramics by precisely controlling densification, microstructure, and properties.
CK-2:IL15 Hybrid Improper Ferroelectricity in La2SrSc2O7-based Ceramics
XIAOQIANG LIU, ZHE GUO, YULU WEI, XIANGMING CHEN, School of Materials Science and Engineering, Zhejiang University, Hangzhou, China
Hybrid Improper Ferroelectrics (HIFs) have attracted considerable attention due to their potential for realizing room temperature multiferroicity with strong magnetoelectric coupling. HIFs exhibit a unique ferroelectric polarization induced by a complex distortion pattern involving two oxygen octahedral tilting modes. These materials are expected to be prevalent in perovskite and layered perovskite structures, as the ubiquitous distortions of oxygen octahedra occur in perovskite-related compounds. Very recently, the HIF has been discovered in A-site cation disorder La2SrSc2O7 ceramic with double-layered Ruddlesden-Popper structure, indicating the possibility of creating single-phase multiferroic in these materials since the Sc3+ can be readily replaced by the magnetic ions, such as, Fe3+. In the present work, single phase La2Sr(Sc1-xFex)2O7 ceramics were prepared, and the room-temperature ferroelectric properties have been investigated. The linear relationship between the Curie temperature and the content of Fe3+ cations has been found. Moreover, the room-temperature ferroelectricity is also observed in Ln2SrSc2O7 (Ln = Nd, Sm) ceramics, and the phase transition is studied by the In-situ X-ray diffraction.
CK-2:L16 Antiferroelectric Ceramics for Piezocatalysis
W. AMDOUNI1, A. ABASS SHAH2, M. OTONIČAR2, B. DKHIL1, 1Université Paris-Saclay, CentraleSupélec, UMR CNRS 8580, Laboratoire Structures, Propriétés et Modélisation des Solides, Gif-Sur-Yvette, France; 2Jožef Stefan Institute, Ljubljana, Slovenia
Piezocatalysis, in which ferroelectrics and piezoelectrics are generally used, is an emerging means of tackling the energy crisis and protecting the environment.[1] To strongly favor the piezocatalysis process, by selecting Sm-substituted BiFeO3 materials, our group has very recently, demonstrated an original approach consisting in using antiferroelectrics, which although not piezoelectric, counter-intuitively exhibit ultrahigh piezodegradation efficiencies for several pollutants reaching up to 100% in 30 min under ultrasonic stimulus. We have also demonstrated that beyond piezodegradation of pollutants, antiferroelectric materials are also good candidates for the production of H2O2 from water.[2] Here, despite the fact that the high catalytic efficiency is mostly achieved with nanoparticles due to high-surface to volume ratio, we show for the first time that NaNbO3-based ceramics display as well significantly greater efficiencies than previously reported ferroelectric and piezoelectric systems. These findings provide a new avenue for designing future antiferroelectric piezocatalysts with high performance for applications that include depollution, production of chemicals or biomedical technologies.
[1] W. Amdouni et al., Adv. Mater. 2023; [2] W.Amdouni et al., Nature, Submitted.
CK-2:L17 Enhanced Energy Storage in Lead-Free BaTiO3–Bi(Mg1/2Ti1/2)O3 Relaxor Ferroelectric Ceramics via Nanoscale Polarization Mismatch and Reconstruction
S. SAHU, P. DOBBIDI, Department of Physics, Indian Institute of Technology Guwahati, Assam, India; D. KALYANI, Department of Zoology, Adikavi Nannaya University, Rajamahendravaram, India
Progress in energy storage ceramics has attracted significant attention due to their environmentally friendly nature and superior ferroelectric/dielectric performance. In this study, lead-free (1−x)BaTiO3–xBi(Mg1/2Ti1/2)O3 (x = 0.05–0.20) relaxor ferroelectric ceramics are synthesized and identified as promising candidates for high-performance energy storage applications. Herein, an effective strategy is proposed to achieve enhanced energy storage performance through nanoscale polarization mismatch and reconstruction, realized by developing solid solutions involving A-site and B-site coupled ferroelectrics. Temperature-dependent dielectric measurements (133–473 K, 1–100 MHz) revealed dieletric value increased from 1094.54 (BT–BMT1) to 1362.28 (BT–BMT3) at 1 MHz, then decreased to 951.44 (BT–BMT4), with the transition temperature shifting from 393 K to 413 K and slightly reducing to 408 K for higher BMT content. The BT–BMT3 showed the best performance, achieving a maximum dielectric constant of 1362.28 at 1 MHz, a transition temperature (413 K), low dielectric loss (0.09), and minimal conductivity. Notably, an ultrahigh recoverable energy density (Wrec) of 2.52 J/cm3 and an efficiency (η) of 71% are obtained, confirming BT–BMT3 as a promising lead-free energy storage systems.
CK-2:L18 Role of Incommensurate Modulation in Tetragonal Tungsten Bronze Ferroelectrics
YI BANG OU, XIAO LI ZHU, JIA WEN SONG, XIANG MING CHEN, School of Materials Science and Engineering, Zhejiang University, Hangzhou, China
The role of incommensurate (IC) modulation in evolution of the pinched polarization-electric field (P-E) hysteresis loops has been investigated and discussed based on the structure and polarization evolution in Ba4(Sm1-xLax)2Ti4Nb6O30 tetragonal tungsten bronzes. Relaxor behavior in the La rich compound is accompanied by the IC modulation structure. Introduction of smaller Sm in the system increases the driving force for the transition from an IC modulation structure to a commensurate superstructure, which coupled with the ferroelectric transition in the middle composition with x = 0.5. In the Sm rich compounds, IC modulation structure reappears as a metastable state to balance the structural instability caused by the too small average ionic radius of the rare-earth ion, meanwhile the field-induced transition from IC modulation structure to commensurate superstructure is confirmed by the selected area electron diffraction (SAED) using an in-situ bias technique as the structural origin for the pinched P-E loops. A phase diagram has been established by combining the ferroelectric phase transition and the modulation structure transition, and a new region with both very small A-site size (A1+A2)/2 and A1-site tolerance factor (tA1) related to the ferroelectric compounds with pinched P-E loops (pinched FE) were added into the previously reported crystal-chemical framework. The present work expands the composition−structure−properties relationships in tungsten bronze ferroelectrics by including the recently reported “pinched FE”, and meanwhile extends the composition manipulation ranges from crossover between relaxor and normal ferroelectrics to ferroelectrics with pinched P-E loops.
CK-2:L19 Textured KNN Based Lead Free Piezoceramics via Templated Grain Growth
N. YÜRÜK1,2, E. SUVACI1,2, 1Eskisehir Technical University, Department of Materials Science and Engineering, Eskisehir, Türkiye; 2Entekno Industrial, Technological and Nano Materials Corp, Eskişehir, Turkey
Lead-based piezoceramics are widely used in transducers, which are the main components of ultrasonic and sensor technologies. The primary reason is that the electrical properties of currently produced lead-free materials remain significantly lower than those of lead-based ceramics. However, the release of lead into the environment continues to cause increasing harm K₀.₅Na₀.₅NbO₃ (KNN) have gained attention, particularly through studies involving Li, Sb, and Ta dopants, as well as textured microstructures produced using NaNbO₃ plate templates. These developments have led to reported d₃₃ values as high as 400–700 pC/N. In this study, the effect of Li addition on the electrical properties of KNN-based ceramics was investigated using uniaxial pressing and <00l>-oriented NaNbO₃ plate templates. It has been shown that textured microstructures can be achieved via Templated Grain Growth process. In the presentation, effects of template content, shaping technique, shaping conditions and sintering conditions on texture development and piezoelectric coefficients (d₃₃) will be discussed.
CK-2:L21 Macroscopic Tin Monochalcogenide Van der Waals Ferroics: Growth, Domain Structures, Curie Temperatures and Lateral Heterostructures
E. SUTTER, Department of Mechanical & Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA; P. SUTTER, Department of Electrical & Computer Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA
Layered (van der Waals) crystals promise new families of ferroics with switchable electric polarization, strain, or magnetic order. So far, synthesis was limited to small (few microns) crystals, where proximity to edges affects domain patterns and limits the achievable device architectures. Here, we report the realization of in-plane ferroelectric/elastic few-layer monochalcogenide (SnS, SnSe) crystals whose dimensions exceed the state of the art by one order of magnitude. Such large crystals allow investigating ferroic domains unaffected by finite size effects. Analysis by in-situ electron microscopy and diffraction shows two distinct domain types, provides measurements of Curie temperatures, and sheds light on symmetry breaking and the transition between the polar and the symmetric (high-T) phase.1,2 Finally, we demonstrate the integration of such monochalcogenides into heterostructures,3 where domain patterns and the low-symmetry (polar) structure can be templated across interfaces. The combined results demonstrate industrial-scale van der Waals ferroics and heterostructures presenting extraordinary opportunities for manipulating ferroelectric order.
1. J. Am. Chem. Soc. 146, 31961 (2024); 2. Proc. Nat. Acad. Sci. 122, e2501509122 (2025); 3. ACS Nano 18, 30829 (2024).
CK-3 Thermoelectric ceramics
CK-3:IL22 Bond Covalency and Carrier-Phonon Coupling in Oxyselenides
JIHUI YANG, Department of Materials Science and Engineering, University of Washington, Seattle, WA, USA
BiCuSeO oxyselenides are attractive thermoelectric materials for intermediate temperatures, owing to their ultralow lattice thermal conductivity and large Seebeck coefficient. Their thermoelectric performance, however, is constrained by intrinsically low carrier mobility. In this talk, we demonstrate that strengthening chemical bond covalency reduces the effective mass and weakens carrier–phonon coupling, thereby enhancing carrier mobility. Te-doping further improves mobility while maintaining electrical conductivity and sustaining high power factors, even at lower carrier concentrations. At the same time, hierarchical structural features—including dual point defects, nanoinclusions, and grain boundaries—formed during nonequilibrium self-propagating high-temperature synthesis (SHS), drive the lattice thermal conductivity toward the amorphous limit. Altogether, our findings show that tuning chemical bonding to mitigate carrier–phonon interactions provides a promising pathway to further improve the thermoelectric performance of BiCuSeO.
CK-3:IL23 WOx/CuOx Heterojunction Optoelectronic Memristive Synapses for Face Recognition Application
TSEUNG-YUEN TSENG, Institute of Electronics, National Yang Ming Chiao Tung University, Taiwan
The impact of annealing on the performance of memristive devices fabricated by WOx/CuOx p-n films sandwiched between ITO electrodes is investigated. The device has low SET and RESET voltages, stable and robust AC endurance of up to 106 cycles, and can retain the states for more than 104 s. The device demonstrates synaptic capabilities by emulating neural functions under both electrical and light stimuli. The behaviors including long-term potentiation/depression, paired-pulse facilitation, spike-timing-dependent plasticity, fully tunable relaxation time of short-term memory, mimicking the temporal dynamics of the biological neuron are declared. A convolutional neural network operation is conducted by exploiting the synaptic functions of the device. The high accuracy of 96.67% with high noise tolerance (close to an ideal synapse) can be achieved. Material analyses are conducted and switching/synaptic mechanisms are proposed to explain such phenomena.
CK-3:IL24 Controlling the Electrical Properties of Perovskites Using Defect Chemistry
D.C. SINCLAIR, University of Sheffield, School of Chemical, Materials and Biological Engineering, Sheffield, UK
Alkaline earth titanate (Ba,Sr)TiO3 (BST) and alkali niobate (Na,K)NbO3 (KNN) perovskites exhibit a diversity of electrical properties based on various donor and/or acceptor dopant mechanisms. Here we survey the influence of A-site donor doping mechanisms via electronic and/or ionic compensation mechanisms to modify the electrical properties of BST and NaNbO3 (NN). The dominant doping mechanisms are different in BST and NN and this has implications for applications as either thermoelectrics, high energy density dielectrics or mixed conducting electrode materials. It also has consequences for further modification of their electrical properties when they are processed in reducing atmospheres to induce oxygen-loss and promote high levels of electronic conduction via mixed Ti3+/Ti4+ and Nb4+/Nb5+ oxidation states.
CK-3:IL25 Half-Heusler Thermoelectrics with Tunable Vacancy Orders
TIEJUN ZHU, State Key Laboratory of Silicon and Advanced Semiconductor Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, P.R. China
Semiconducting half-Heusler compounds with the valence electron count of 18 have been identified as a class of promising high-temperature thermoelectric materials. Recently, nominal 19-electron half-Heusler compounds, possessing massive intrinsic vacancies at the cation site and intrinsically low lattice thermal conductivity, have gained reacquaintance and popularity due to their unexpected high thermoelectric performance and fascinating defective structure. In this talk, we introduce the current progress of half-Heusler thermoelectric materials, the discovery and challenge of new cation-deficent half-Heusler compounds with the vacancy-related short-range order, and the transition between the short range order and long range order. The relationship between the vacancy order and physical properties are established and explained.
CK-3:L25b Ductile Semiconductors and their Thermoelectric Properties
XUN SHI, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China
We report the recently discovered ductile inorganic semiconductor materials such as Ag2S and its alloys, and defective Bi2Te3-based materials. They are typical semiconductors with excellent thermoelectric performance. At the same time, they are highly plastic, which are similar with the mechanical properties of metals. Furthermore, upon compositional optimization, these ductile materials can reach a delicate balance between high carrier mobility, power factor, a figure of merit and good mechanical plasticity. The good ductile thermoelectric materials open a new avenue for the fabrication of flexible and other new thermoelectric devices. These results promised an emerging paradigm and market of thermoelectric materials and devices.
CK-4 Caloric ceramics
CK-4:IL26 Development of Electrocaloric Multilayer Capacitors for Energy-efficient Cooling Applications
SAKYO HIROSE, Murata Manufacturing Co., Ltd., Nagaokakyo, Kyoto, Japan
The electrocaloric (EC) effect, a reversible thermal change induced by an electric field, occurs in ferroelectric and antiferroelectric materials, and it has gained considerable attention as a promising basis for next-generation solid-state cooling. Due to the urgent need for environmentally friendly and energy-efficient cooling solutions, substantial research efforts have focused on EC materials and cooling prototypes. At Murata manufacturing, we utilized our well-established multilayer capacitor (MLC) technology—originally developed for capacitor and piezoelectric applications—to design and fabricate EC MLCs with extremely high breakdown strength and large EC responses near room temperature. In the MLCs of highly ordered PbSc0.5Ta0.5O3 (PST), we achieved an adiabatic temperature change of approximately 5 K around room temperature and supplied MLCs of PST for the development of regenerative EC cooling systems. Recently, we have expanded our work to novel solid-solution compositions, PST-PbMg0.5W0.5O3, to improve performance and extend the operating temperature window. In my presentation, I will highlight recent progress in EC materials and MLC device development and outline pathways toward energy-efficient cooling technologies.
CK-4:IL27 Electrocaloric Cooling Efficiency: Comparative Insights on P(VDF-TrFE-CFE) Polymer and BSTM Ceramics
M. ALMANZA1,2, S. SADHUKHAN1, N. ZEGGAI1, B. DKHIL2, M. LOBUE1, 1Université Paris-Saclay, ENS Paris-Saclay, CNRS, SATIE, Gif-sur-Yvette, France; 2Université Paris-Saclay, CentraleSupélec, CNRS, Laboratoire SPMS, Gif-sur-Yvette, France
In response to the increasing demand for efficient and compact refrigeration and energy conversion devices, research has focused on identifying optimal electrocaloric (EC) materials among ferroelectric ceramics and polymers. This study investigates the EC properties of the Poly [(Vinylidene Fluoride)0.664-(Trifluoroethylene)0.245-(Chlorofluoroethylene)0.91] terpolymer and multi-layer ceramic Ba0.6Sr0.4Ti0.998Mn0.002O3 (BSTM) ceramics, comparing various parameters to assess their suitability for electrocaloric cooling. Adiabatic temperature change (ΔTad) are measured with direct method and with electric field compatible with long-term operation. The loss in ferroelectric hysteresis is observed to be much lower in BSTM than in PVDF Terpolymer. Hence, the resulting Cooling efficiency, computed over a thermodynamic cycle mimicking Carnot efficiency, reveals that the PVDF Terpolymer achieves a relative cooling efficiency lower than the BSTM ceramics. The PVDF Terpolymer outperforms BSTM ceramics in terms of adiabatic temperature change but not in terms of expected cooling efficiency. Through our methodology it reveals that both BSTM ceramics and PVDF terpolymers emerge as promising electrocaloric materials for solid-state cooling but they have complementary strengths. We would also like to thank Murata, Piezotech Arkema for their samples.
CK-5 Semiconducting and fast ion-conducting ceramics
CK-5:IL28 Long Term Materials Performance in High Temperature Electrochemical Systems
P. SINGH, P.K. DUBEY, University of Connecticut, Storrs, CT, USA; T. SUZUKI, Precision Combustion Inc., New Haven, CT, USA
Status of oxygen ion and proton conducting high temperature solid state electrochemical technologies for power generation and hydrogen production are reviewed. Recent advances and research trends in electrochemical cell and stack materials selection and fabrication processes are discussed. Experimental observations on long-term electrochemical performance and structural changes are examined and presented. Thermochemical and electrochemical reactions and processes responsible for the above degradation along with related degradation mechanisms are discussed. Surface, interface and bulk degradation in electrochemically active and in-active cell / stack components are examined and their role on irreversible changes in the ohmic and non-ohmic polarization losses are discussed. This presentation will focus on electrode and electrolyte (doped perovskites/ fluorites) structural and chemical changes during exposure to humid atmospheres containing trace gaseous impurities (at ppm/ppb levels). Processes related to dopant exsolution, trace contaminant interaction and electrode poisoning under anodic and cathodic conditions will be described. Accelerated metal corrosion under H2-H2O redox and bi-polar exposure conditions will be discussed with emphasis on the breakdown of passivation and formation of localized non-protective surface scale. Phenomena related to Hydrogen permeation in metal, hydrogen interaction with metal impurities and porosity formation will be discussed.
CK-5:IL29 3D Printed BaTiO3-based Semiconducting Ceramics with High PTC Effect
WEN ZHENG, XI CHEN, BINGXIAO XUE, TIANWEN DONG, KAIXIN CHEN, WEI LUO, QIUYUN FU, School of Integrated Circuit, Engineering Research Center for Functional Ceramics of Ministry of Education, Huazhong University of Science and Technology, Wuhan, Hubei, P.R. China
The realization of complex structures using emerging vat photopolymerization (VPP) technology is limited by the poor curing properties of leaded PTC ceramic slurry. Herein, this study presents an innovative approach of combining VPP technology with vacuum infiltration (VI) process for fabricating high-performance PTC ceramics. Notably, the introduction of soluble starch significantly enhances the curing depth and printability of PTC ceramic slurry. Meanwhile, silica nanoparticles in silica sols are infiltrated into 3D printed green bodies to improve the electrical properties of PTC ceramics. At optimal soluble starch content and silica concentration, a lower room temperature resistivity (ρ=207 Ω·cm) and a higher temperature coefficient of resistance (α0-15=25.14 %/℃) are obtained in printed PTC ceramics compared to dry pressed PTC ceramics (ρ=301 Ω·cm, α0-15=19.32 %/℃). Therefore, this work provides a novel technological strategy for fabricating high-performance PTC ceramics with desirable structures and can promote the wide application of PTC heating elements.
CK-5:IL30 Progress in Protonic Ceramic Electrolysis Cells (PCECs)
S. RICOTE, Y. SHIN, R.J. KEE, Colorado School of Mines, Golden, CO, USA
Protonic Ceramic Electrolysis Cells (PCECs) are an emerging technology for hydrogen production that operates efficiently within the intermediate temperature range of 400–600 °C. With growing scientific interest and promising electrochemical performance, PCECs hold potential. However, critical challenges still hinder their path to commercialization, namely, low Faradaic efficiency under certain conditions, demanding requirements for steam electrode (positrode) materials, and the need for scalable, cost-effective manufacturing processes. Following an introduction to protonic ceramics and a review of recent advancements in PCECs, this presentation will explore strategies for developing advanced positrode materials using composite designs. It will also examine the dependence of Faradaic efficiency on key operating conditions, such as temperature and gas composition. Finally, the talk will propose methods to improve Faradaic efficiency and introduce a measurement protocol designed to reduce experimental uncertainty.
CK-5:L31 High Temperature Dielectric Properties of Graphitic-carbon Coated 8YSZ Nanoplatelets
A. MISHRA, S. BISWAS, Dept. of Physics, The LNM Institute of Information Technology, Jaipur, Rajasthan, India
High temperature dielectric properties of graphitic-carbon coated 8.0 mole% Y2O3-stabilized ZrO2 (8YSZ) nanoparticles (NPs) were studied in ambient air. The platelet-shaped NPs were synthesized by a simple chemical process. The process permits fine-tuning of the morphology of the NPs along with the formation of an in situ grown surface layer of graphitic-carbon. The morphology and surface structure of the 8YSZ NPs were studied by high resolution transmission electron microscope and Raman spectroscopy. The graphitic-carbon layer plays a critical role in controlling the dielectric properties of the 8YSZ nanoplatelets. In this paper, we report on the high temperature dielectric characteristics of the 8YSZ nanoplatelets in correlation with their surface structure.