K0.5Na0.5NbO3 is among the most promising lead-free piezoelectrics. While its sputtered films match the performance of the champion piezoelectric Pb(Zr,Ti)O3, reproducible processing of high-quality and time-stable solution-deposited K0.5Na0.5NbO3 films remains challenging. Here, we report 1 µm-thick Mn-doped K0.5Na0.5NbO3 films prepared via a chemical solution deposition process, which have perfectly dense microstructure and uniform composition across their thickness. The films exhibit a high transverse piezoelectric coefficient (e31,f = −15.4 C/m2), high dielectric permittivity (εr ≈ 920), low dielectric losses (tanδ = 0.05) and can withstand electric fields up to at least 1 MV/cm. Their functional properties show excellent stability over time, and the synthesis process is reproducible. Furthermore, a surface acoustic haptic device based on K0.5Na0.5NbO3 thin-film actuators is demonstrated. The results validate the high potential of Mn-doped K0.5Na0.5NbO3 films to replace lead-based Pb(Zr,Ti)O3 films in piezoelectric applications.
{"title":"Solution-based fabrication of high-performance K0.5Na0.5NbO3 thin films for surface haptics","authors":"Nagamalleswara Rao Alluri , Longfei Song , Stephanie Girod , Barnik Mandal , Juliette Cardoletti , Vid Bobnar , Torsten Granzow , Veronika Kovacova , Adrian-Marie Philippe , Emmanuel Defay , Sebastjan Glinsek","doi":"10.1016/j.jeurceramsoc.2025.118077","DOIUrl":"10.1016/j.jeurceramsoc.2025.118077","url":null,"abstract":"<div><div>K<sub>0.5</sub>Na<sub>0.5</sub>NbO<sub>3</sub> is among the most promising lead-free piezoelectrics. While its sputtered films match the performance of the champion piezoelectric Pb(Zr,Ti)O<sub>3</sub>, reproducible processing of high-quality and time-stable solution-deposited K<sub>0.5</sub>Na<sub>0.5</sub>NbO<sub>3</sub> films remains challenging. Here, we report 1 µm-thick Mn-doped K<sub>0.5</sub>Na<sub>0.5</sub>NbO<sub>3</sub> films prepared via a chemical solution deposition process, which have perfectly dense microstructure and uniform composition across their thickness. The films exhibit a high transverse piezoelectric coefficient (<em>e</em><sub><em>31</em>,f</sub> = −15.4 C/m<sup>2</sup>), high dielectric permittivity (<em>ε</em><sub>r</sub> ≈ 920), low dielectric losses (tan<em>δ</em> = 0.05) and can withstand electric fields up to at least 1 MV/cm. Their functional properties show excellent stability over time, and the synthesis process is reproducible. Furthermore, a surface acoustic haptic device based on K<sub>0.5</sub>Na<sub>0.5</sub>NbO<sub>3</sub> thin-film actuators is demonstrated. The results validate the high potential of Mn-doped K<sub>0.5</sub>Na<sub>0.5</sub>NbO<sub>3</sub> films to replace lead-based Pb(Zr,Ti)O<sub>3</sub> films in piezoelectric applications.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 6","pages":"Article 118077"},"PeriodicalIF":6.2,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145798202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-11DOI: 10.1016/j.jeurceramsoc.2025.118079
Jialiang Zhang, Lu Li, Fengyun Liu
The (K,Na)NbO3-based ceramics are an attractive type of lead-free piezoelectric materials. However, due to polymorphic phase transitions, obtaining an excellent comprehensive piezoelectric performance of high piezoelectric coefficient d33, large electromechanical coupling factors (representatively, kp, kt and k33) and good thermal stabilities of weak temperature dependence and little thermal-ageing degradation is significantly challenging. The 0.965(K0.48Na0.52)0.99Li0.01(Nb0.98Sb0.02)O3-0.035(Bi0.50Na0.50)ZrO3 composition was recently found to possess a great potential for resolving the issue. Its ordinary ceramic exhibits considerably good piezoelectric properties and thermal stabilities. The < 001> textured ceramic has a highly diffused orthorhombic-tetragonal phase transition, and shows a further enhanced temperature stability. It has d33 of 370 pC/N with little change up to 170 °C, and its kp varies between 0.605 and 0.525 in the temperature range from −60 °C to 150 °C. In general, this textured ceramic is well comparable to the famous commercial soft PZT-5A, and thus provides a large possibility for practical device applications.
{"title":"Excellent comprehensive piezoelectric performance of textured 0.965(K0.48Na0.52)0.99Li0.01(Nb0.98Sb0.02)O3-0.035(Bi0.50Na0.50)ZrO3 ceramic","authors":"Jialiang Zhang, Lu Li, Fengyun Liu","doi":"10.1016/j.jeurceramsoc.2025.118079","DOIUrl":"10.1016/j.jeurceramsoc.2025.118079","url":null,"abstract":"<div><div>The (K,Na)NbO<sub>3</sub>-based ceramics are an attractive type of lead-free piezoelectric materials. However, due to polymorphic phase transitions, obtaining an excellent comprehensive piezoelectric performance of high piezoelectric coefficient <em>d</em><sub>33</sub>, large electromechanical coupling factors (representatively, <em>k</em><sub>p</sub>, <em>k</em><sub>t</sub> and <em>k</em><sub>33</sub>) and good thermal stabilities of weak temperature dependence and little thermal-ageing degradation is significantly challenging. The 0.965(K<sub>0.48</sub>Na<sub>0.52</sub>)<sub>0.99</sub>Li<sub>0.01</sub>(Nb<sub>0.98</sub>Sb<sub>0.02</sub>)O<sub>3</sub>-0.035(Bi<sub>0.50</sub>Na<sub>0.50</sub>)ZrO<sub>3</sub> composition was recently found to possess a great potential for resolving the issue. Its ordinary ceramic exhibits considerably good piezoelectric properties and thermal stabilities. The < 001> textured ceramic has a highly diffused orthorhombic-tetragonal phase transition, and shows a further enhanced temperature stability. It has <em>d</em><sub>33</sub> of 370 pC/N with little change up to 170 °C, and its <em>k</em><sub>p</sub> varies between 0.605 and 0.525 in the temperature range from −60 °C to 150 °C. In general, this textured ceramic is well comparable to the famous commercial soft PZT-5A, and thus provides a large possibility for practical device applications.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 6","pages":"Article 118079"},"PeriodicalIF":6.2,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145798191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-10DOI: 10.1016/j.jeurceramsoc.2025.118073
Qiang Liu , Xiaxue Zhang , Huiting Luo , Kai Cui , Lingjiao Zhan , Shuwei Yao
The phase transformation pathways in alumina-mullite ceramics are strongly influenced by precursor morphological dimensionality, where atomic-scale coordination environments are shown to critically affect crystallization kinetics. Through sol-gel synthesis of three distinct architectures—powders, nanofibers, and microfibers—we demonstrate that morphological scale controls the formation of aluminum coordination defects during pyrolysis. XRD and TEM analyses established morphology-dependent phase evolution: microfibers directly crystallize into orthorhombic mullite above 1000 °C, while nanofibers undergo sequential γ→θ alumina transitions prior to mullitization. Solid-state 27Al MAS NMR revealed that microfibers develop substantial pentacoordinated Al (AlO5), suggesting the generation of anionic vacancies that facilitate Si infiltration and enable mullite nucleation at temperatures as low as 800 °C. In contrast, nanofibers predominantly retain octahedral/tetrahedral Al configurations, which appear to impose kinetic barriers to Al/Si interdiffusion and preferentially stabilize γ-Al2O3. This work supports a vacancy-mediated diffusion mechanism, demonstrating that morphological engineering can effectively guide phase selection in multicomponent ceramic systems.
氧化铝-莫来石陶瓷的相变路径受前驱体形态维度的强烈影响，其中原子尺度的配位环境对结晶动力学有重要影响。通过溶胶-凝胶合成三种不同的结构——粉末、纳米纤维和微纤维——我们证明了形态尺度控制了热解过程中铝配位缺陷的形成。XRD和TEM分析表明，微纤维在1000℃以上直接结晶为正交莫来石，而纳米纤维在莫来石化之前经历了顺序的γ→θ氧化铝转变。固态27Al MAS NMR显示，微纤维产生了大量的五配位Al (AlO5)，这表明阴离子空位的产生促进了Si的渗透，并使莫来石在低至800℃的温度下成核。相比之下，纳米纤维主要保留八面体/四面体Al构型，这似乎对Al/Si相互扩散施加了动力学障碍，并优先稳定γ-Al2O3。这项工作支持了空位介导的扩散机制，表明形态工程可以有效地指导多组分陶瓷系统的相选择。
{"title":"From powders to microfibers: Morphology-dependent phase transformation pathways in alumina-mullite ceramics","authors":"Qiang Liu , Xiaxue Zhang , Huiting Luo , Kai Cui , Lingjiao Zhan , Shuwei Yao","doi":"10.1016/j.jeurceramsoc.2025.118073","DOIUrl":"10.1016/j.jeurceramsoc.2025.118073","url":null,"abstract":"<div><div>The phase transformation pathways in alumina-mullite ceramics are strongly influenced by precursor morphological dimensionality, where atomic-scale coordination environments are shown to critically affect crystallization kinetics. Through sol-gel synthesis of three distinct architectures—powders, nanofibers, and microfibers—we demonstrate that morphological scale controls the formation of aluminum coordination defects during pyrolysis. XRD and TEM analyses established morphology-dependent phase evolution: microfibers directly crystallize into orthorhombic mullite above 1000 °C, while nanofibers undergo sequential γ→θ alumina transitions prior to mullitization. Solid-state <sup>27</sup>Al MAS NMR revealed that microfibers develop substantial pentacoordinated Al (AlO<sub>5</sub>), suggesting the generation of anionic vacancies that facilitate Si infiltration and enable mullite nucleation at temperatures as low as 800 °C. In contrast, nanofibers predominantly retain octahedral/tetrahedral Al configurations, which appear to impose kinetic barriers to Al/Si interdiffusion and preferentially stabilize γ-Al<sub>2</sub>O<sub>3</sub>. This work supports a vacancy-mediated diffusion mechanism, demonstrating that morphological engineering can effectively guide phase selection in multicomponent ceramic systems.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 6","pages":"Article 118073"},"PeriodicalIF":6.2,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145749574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-10DOI: 10.1016/j.jeurceramsoc.2025.118075
Ruixiong zhai , Taihong Huang , Dehao Kong , Qingshan Yang , Tao Wang , Chen Hua , Xiping Xiong , Yuwei Liang , Peng Song
To overcome the protection failure of MoSi2 coatings caused by the poor stability of the oxide scale at ultra-high temperatures, a solid solution film-forming strategy was proposed. The MoSi2–ZrB2 composite coating was successfully fabricated, and its erosion resistance at 1800 °C was systematically investigated. The results demonstrated that the MoSi2-ZrB2 composite coating exhibited superior high temperature erosion protection. After the ultra-high temperature erosion test, the mass erosion rate of MoSi2-ZrB2 composite coating was 0.013 mg/s, which is obviously lower than that the MoSi2 coating (0.133 mg/s). Compared to the MoSi2 coating, the MoSi2-ZrB2 composite coating maintained a dense and crack-free oxide scale. The enhanced performance originates from the formation of a highly stable composite glass phase (SiO2-ZrO2/ZrSiO4). Furthermore, the in-situ formation of the MoB phase effectively suppressed gases volatilization, synergistically improving the structural stability of the oxide layer and its oxygen-blocking capability.
{"title":"Boosting the ultra-high temperature erosion stability of MoSi2 coating at 1800 ℃ by solid solution film-forming","authors":"Ruixiong zhai , Taihong Huang , Dehao Kong , Qingshan Yang , Tao Wang , Chen Hua , Xiping Xiong , Yuwei Liang , Peng Song","doi":"10.1016/j.jeurceramsoc.2025.118075","DOIUrl":"10.1016/j.jeurceramsoc.2025.118075","url":null,"abstract":"<div><div>To overcome the protection failure of MoSi<sub>2</sub> coatings caused by the poor stability of the oxide scale at ultra-high temperatures, a solid solution film-forming strategy was proposed. The MoSi<sub>2</sub>–ZrB<sub>2</sub> composite coating was successfully fabricated, and its erosion resistance at 1800 °C was systematically investigated. The results demonstrated that the MoSi<sub>2</sub>-ZrB<sub>2</sub> composite coating exhibited superior high temperature erosion protection. After the ultra-high temperature erosion test, the mass erosion rate of MoSi<sub>2</sub>-ZrB<sub>2</sub> composite coating was 0.013 mg/s, which is obviously lower than that the MoSi<sub>2</sub> coating (0.133 mg/s). Compared to the MoSi<sub>2</sub> coating, the MoSi<sub>2</sub>-ZrB<sub>2</sub> composite coating maintained a dense and crack-free oxide scale. The enhanced performance originates from the formation of a highly stable composite glass phase (SiO<sub>2</sub>-ZrO<sub>2</sub>/ZrSiO<sub>4</sub>). Furthermore, the in-situ formation of the MoB phase effectively suppressed gases volatilization, synergistically improving the structural stability of the oxide layer and its oxygen-blocking capability.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 6","pages":"Article 118075"},"PeriodicalIF":6.2,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145749572","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-09DOI: 10.1016/j.jeurceramsoc.2025.118072
Haolong Zheng , Weiwei Zhu , Mu Tang , Haohao Zou , Guoqing Zu , Ying Han , Xu Ran
In this study, the La2O3-Y2O3-B2O3-SiO2 glass filler was used to join zirconia toughened alumina (ZTA) ceramics. The three-dimensional interlocking interface structure formed between the brazing seam and the ceramic due to the in-situ dissolution of ZrO2 from the substrate, leading a strong interfacial bonding. Crystallization treatment promoted the formation of YNbO4 and Al2O3, which reduced the coefficient of thermal expansion (CTE) difference between the brazing seams and the ZTA ceramics. Owing to the improved interface structure and the matched CTE, the joints reached a flexural strength of 530 ± 20 MPa.
{"title":"Fabrication of ZTA/ZTA joints with high strength based on interface interlocking strategy by using glass filler","authors":"Haolong Zheng , Weiwei Zhu , Mu Tang , Haohao Zou , Guoqing Zu , Ying Han , Xu Ran","doi":"10.1016/j.jeurceramsoc.2025.118072","DOIUrl":"10.1016/j.jeurceramsoc.2025.118072","url":null,"abstract":"<div><div>In this study, the La<sub>2</sub>O<sub>3</sub>-Y<sub>2</sub>O<sub>3</sub>-B<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub> glass filler was used to join zirconia toughened alumina (ZTA) ceramics. The three-dimensional interlocking interface structure formed between the brazing seam and the ceramic due to the in-situ dissolution of ZrO<sub>2</sub> from the substrate, leading a strong interfacial bonding. Crystallization treatment promoted the formation of YNbO<sub>4</sub> and Al<sub>2</sub>O<sub>3</sub>, which reduced the coefficient of thermal expansion (CTE) difference between the brazing seams and the ZTA ceramics. Owing to the improved interface structure and the matched CTE, the joints reached a flexural strength of 530 ± 20 MPa.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 6","pages":"Article 118072"},"PeriodicalIF":6.2,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145798199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-08DOI: 10.1016/j.jeurceramsoc.2025.118065
Ye Guo , Bing Chen , Rukai Liu , Junchang Liu , Fei Su , Zhaohui Deng
To address the oversimplification of abrasive morphology and composite structure in current 2.5D C/SiC composite scratching simulations, this study constructed a truncated octahedral abrasive model and established unidirectional (UD) and short-fiber reinforced polymer (SFRP) representative volume elements according to the composite's typical regional features. Four typical fiber region scratching simulations were conducted. Combined with experimental data, including scratching force, surface morphology, contour curves, and acoustic emission signals, material removal mechanisms were analyzed in depth. The results show that different fiber regions exhibit distinct mechanical responses and damage modes, influenced by carbon fiber anisotropy. At the same scratching depth, average force decreases in the order: 90° fiber region, needled fiber region, 0° fiber region, and SFRP region. With increasing depth, 90° region damage extends primarily longitudinally, while 0° region damage expands mainly transversely with less longitudinal extension. SFRP and needled regions show lighter damage in both directions.
{"title":"Scratching of 2.5D C/SiC composites considering real abrasive morphology and material microstructure: Microscopic simulation and experimental study","authors":"Ye Guo , Bing Chen , Rukai Liu , Junchang Liu , Fei Su , Zhaohui Deng","doi":"10.1016/j.jeurceramsoc.2025.118065","DOIUrl":"10.1016/j.jeurceramsoc.2025.118065","url":null,"abstract":"<div><div>To address the oversimplification of abrasive morphology and composite structure in current 2.5D C/SiC composite scratching simulations, this study constructed a truncated octahedral abrasive model and established unidirectional (UD) and short-fiber reinforced polymer (SFRP) representative volume elements according to the composite's typical regional features. Four typical fiber region scratching simulations were conducted. Combined with experimental data, including scratching force, surface morphology, contour curves, and acoustic emission signals, material removal mechanisms were analyzed in depth. The results show that different fiber regions exhibit distinct mechanical responses and damage modes, influenced by carbon fiber anisotropy. At the same scratching depth, average force decreases in the order: 90° fiber region, needled fiber region, 0° fiber region, and SFRP region. With increasing depth, 90° region damage extends primarily longitudinally, while 0° region damage expands mainly transversely with less longitudinal extension. SFRP and needled regions show lighter damage in both directions.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 6","pages":"Article 118065"},"PeriodicalIF":6.2,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145749569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-08DOI: 10.1016/j.jeurceramsoc.2025.118071
JangWon Lee , Wataru Nakao
A method was investigated to utilize the competition behavior between crack propagation and crack degeneration due to self-healing in continuous fiber-reinforced self-healing composite ceramics (abbreviated as shFRC) as a new strength criterion. A stationary load test was performed at 1100 °C, and the overall elongation of the test specimen resulting was measured. At 65 MPa and 80 MPa, the crack hardly propagated, and the crack degeneration due to self-healing, so the crack arrest time became constant. At 90 MPa to 110 MPa, competition between crack propagation and crack degeneration due to self-healing occurred, but the crack was arrested. At 125 MPa to 140 MPa, crack propagation was inhibited, but eventually led to fracture. As a result, the maximum stress at which crack propagation due to self-healing can be arrested was determined to be 115 MPa. This stress corresponds to 80 % of the fracture strength and has been named the self-healing limit stress.
{"title":"Fracture criteria of self-healing ceramics determined by the competition between crack propagation and self-healing","authors":"JangWon Lee , Wataru Nakao","doi":"10.1016/j.jeurceramsoc.2025.118071","DOIUrl":"10.1016/j.jeurceramsoc.2025.118071","url":null,"abstract":"<div><div>A method was investigated to utilize the competition behavior between crack propagation and crack degeneration due to self-healing in continuous fiber-reinforced self-healing composite ceramics (abbreviated as shFRC) as a new strength criterion. A stationary load test was performed at 1100 °C, and the overall elongation of the test specimen resulting was measured. At 65 MPa and 80 MPa, the crack hardly propagated, and the crack degeneration due to self-healing, so the crack arrest time became constant. At 90 MPa to 110 MPa, competition between crack propagation and crack degeneration due to self-healing occurred, but the crack was arrested. At 125 MPa to 140 MPa, crack propagation was inhibited, but eventually led to fracture. As a result, the maximum stress at which crack propagation due to self-healing can be arrested was determined to be 115 MPa. This stress corresponds to 80 % of the fracture strength and has been named the self-healing limit stress.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 6","pages":"Article 118071"},"PeriodicalIF":6.2,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145798196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-08DOI: 10.1016/j.jeurceramsoc.2025.118067
Hongji Zou , Jie Li , Ziyi Zhang , Ying Tang , Weiping Gong , Liang Fang
Novel low-permittivity Mg7Ga2GeO12 ceramics with unique crystal structure consisting of rock-salt and β-Ga2O3 blocks were prepared by the solid-state method. When sintered at 1380 °C, it showed ultra-high Q×f = 145,000 ± 300 GHz, low εr = 10.5 ± 0.1, and τf = −50.7 ± 1.0 ppm/°C. The positive deviation between the εr and εr(C–M) (8.7) of 21.2 % was due to the underestimating dielectric polarizability. The Phillips-Van Vechten-Levine (P-V-L) theory results indicated that the (Mg4/Ga1)-O bond had the greatest impact on the εr and thermal stability, while the (Ga5/Ge1)-O bond mainly contributes to lattice energy. The intrinsic dielectric properties were analyzed by infrared reflectivity spectra. To demonstrate its potential for practical applications, a dielectric resonator antenna (DRA) based on Mg7Ga2GeO12 ceramic was designed and fabricated, exhibiting a high gain (6.6 dBi) and radiation efficiency (> 98.3 %).
{"title":"Novel Mg7Ga2GeO12 microwave dielectric ceramics with ultralow-loss and low-permittivity for high-frequency packaging substrate","authors":"Hongji Zou , Jie Li , Ziyi Zhang , Ying Tang , Weiping Gong , Liang Fang","doi":"10.1016/j.jeurceramsoc.2025.118067","DOIUrl":"10.1016/j.jeurceramsoc.2025.118067","url":null,"abstract":"<div><div>Novel low-permittivity Mg<sub>7</sub>Ga<sub>2</sub>GeO<sub>12</sub> ceramics with unique crystal structure consisting of rock-salt and <em>β</em>-Ga<sub>2</sub>O<sub>3</sub> blocks were prepared by the solid-state method. When sintered at 1380 °C, it showed ultra-high <em>Q</em>×<em>f</em> = 145,000 ± 300 GHz, low <em>ε</em><sub><em>r</em></sub> = 10.5 ± 0.1, and <em>τ</em><sub><em>f</em></sub> = −50.7 ± 1.0 ppm/°C. The positive deviation between the <em>ε</em><sub><em>r</em></sub> and <em>ε</em><sub><em>r</em>(C–M)</sub> (8.7) of 21.2 % was due to the underestimating dielectric polarizability. The Phillips-Van Vechten-Levine (P-V-L) theory results indicated that the (Mg4/Ga1)-O bond had the greatest impact on the <em>ε</em><sub><em>r</em></sub> and thermal stability, while the (Ga5/Ge1)-O bond mainly contributes to lattice energy. The intrinsic dielectric properties were analyzed by infrared reflectivity spectra. To demonstrate its potential for practical applications, a dielectric resonator antenna (DRA) based on Mg<sub>7</sub>Ga<sub>2</sub>GeO<sub>12</sub> ceramic was designed and fabricated, exhibiting a high gain (6.6 dBi) and radiation efficiency (> 98.3 %).</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 6","pages":"Article 118067"},"PeriodicalIF":6.2,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145798188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-08DOI: 10.1016/j.jeurceramsoc.2025.118070
Lingzhi Chen , Ce Zheng , Dongying Wang , Yichun Bi , Chaofan Yang , Shengkai Wang , Xiaoqiang Li
Developing a pressure-less joining process operable at tolerable temperatures is crucial for practical engineering deployment of SiCf/SiC thin-walled cladding tubes. Hereby, we invented a low-temperature pressure-less Nano-Infiltration and Transient Eutectic (NITE) joining method for SiCf/SiC composites using Al2O3 and Y2O3 sintering additives, achieving successful bonding at 1600 ℃ for 2.5 h without interfacial debonding. The joint microstructure consisted of SiC with finely distributed Y3Al5O12 intergranular phase, exhibiting excellent integrity and mechanical performance (shear strength of 46.7 ± 2.7 MPa). After 8 h steam oxidation at 1200 ℃, joints retained 77.9 % strength (36.4 ± 6.8 MPa) through protective SiO2/AlOOH layers and Y-silicate transformations. Successful SiCf/SiC cladding tube encapsulation demonstrated technical feasibility, with XCT revealing robust bonding despite minor inner-wall densification issues. This work establishes NITE as a viable solution for nuclear applications, combining favorable processing conditions with superior joint performance.
{"title":"Low-temperature pressure-less joining of SiCf/SiC via NITE sintering: Mechanical performance and steam oxidation resistance","authors":"Lingzhi Chen , Ce Zheng , Dongying Wang , Yichun Bi , Chaofan Yang , Shengkai Wang , Xiaoqiang Li","doi":"10.1016/j.jeurceramsoc.2025.118070","DOIUrl":"10.1016/j.jeurceramsoc.2025.118070","url":null,"abstract":"<div><div>Developing a pressure-less joining process operable at tolerable temperatures is crucial for practical engineering deployment of SiC<sub>f</sub>/SiC thin-walled cladding tubes. Hereby, we invented a low-temperature pressure-less Nano-Infiltration and Transient Eutectic (NITE) joining method for SiC<sub>f</sub>/SiC composites using Al<sub>2</sub>O<sub>3</sub> and Y<sub>2</sub>O<sub>3</sub> sintering additives, achieving successful bonding at 1600 ℃ for 2.5 h without interfacial debonding. The joint microstructure consisted of SiC with finely distributed Y<sub>3</sub>Al<sub>5</sub>O<sub>12</sub> intergranular phase, exhibiting excellent integrity and mechanical performance (shear strength of 46.7 ± 2.7 MPa). After 8 h steam oxidation at 1200 ℃, joints retained 77.9 % strength (36.4 ± 6.8 MPa) through protective SiO<sub>2</sub>/AlOOH layers and Y-silicate transformations. Successful SiC<sub>f</sub>/SiC cladding tube encapsulation demonstrated technical feasibility, with XCT revealing robust bonding despite minor inner-wall densification issues. This work establishes NITE as a viable solution for nuclear applications, combining favorable processing conditions with superior joint performance.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 6","pages":"Article 118070"},"PeriodicalIF":6.2,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145749570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-08DOI: 10.1016/j.jeurceramsoc.2025.118066
Rui-Hua Chen, Suniya Siddique, Hua-Jing Zhang, Ning Chen, Zhuo-Ming Xu, Zi-Long Zhang, Yue-Xing Chen, Zhuang-Hao Zheng, Fu Li
Herein, a Ti/Cu co-doping strategy is employed in Bi2SeS2 to optimize its electrical and thermal transport properties through carrier regulation and microstructure modulation. The Ti/Cu co-doped Bi2SeS2 samples were synthesized by mechanical alloying followed by spark plasma sintering. It is found that the co-doping boosts electrical conductivity while preserving a moderate Seebeck coefficient of 150–200 μV K−1. This yields a high power factor of 5.5 μW cm−1 K−2 at 773 K. Moreover, the lattice thermal conductivity is reduced to ∼0.25 W m−1 K−1, primarily due to effective phonon scattering induced by lattice strain and point defects. Finally, a peak zT of ∼0.80 is achieved at 773 K in Bi1.96Ti0.04SeS2-1 %Cu, surpassing the solely Cu-doped and Ti-doped counterparts by ∼22 % and 40 %, respectively. These findings reveal that multi-element doping is an effective approach for tailoring both charge and phonon transport, providing valuable insights for the design of advanced thermoelectric materials.
{"title":"Synergistic tuning of electrical and thermal transport properties in Bi2SeS2 thermoelectric material via Ti/Cu co-doping","authors":"Rui-Hua Chen, Suniya Siddique, Hua-Jing Zhang, Ning Chen, Zhuo-Ming Xu, Zi-Long Zhang, Yue-Xing Chen, Zhuang-Hao Zheng, Fu Li","doi":"10.1016/j.jeurceramsoc.2025.118066","DOIUrl":"10.1016/j.jeurceramsoc.2025.118066","url":null,"abstract":"<div><div>Herein, a Ti/Cu co-doping strategy is employed in Bi<sub>2</sub>SeS<sub>2</sub> to optimize its electrical and thermal transport properties through carrier regulation and microstructure modulation. The Ti/Cu co-doped Bi<sub>2</sub>SeS<sub>2</sub> samples were synthesized by mechanical alloying followed by spark plasma sintering. It is found that the co-doping boosts electrical conductivity while preserving a moderate Seebeck coefficient of 150–200 μV K<sup>−1</sup>. This yields a high power factor of 5.5 μW cm<sup>−1</sup> K<sup>−2</sup> at 773 K. Moreover, the lattice thermal conductivity is reduced to ∼0.25 W m<sup>−1</sup> K<sup>−1</sup>, primarily due to effective phonon scattering induced by lattice strain and point defects. Finally, a peak <em>zT</em> of ∼0.80 is achieved at 773 K in Bi<sub>1.96</sub>Ti<sub>0.04</sub>SeS<sub>2</sub>-1 %Cu, surpassing the solely Cu-doped and Ti-doped counterparts by ∼22 % and 40 %, respectively. These findings reveal that multi-element doping is an effective approach for tailoring both charge and phonon transport, providing valuable insights for the design of advanced thermoelectric materials.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 6","pages":"Article 118066"},"PeriodicalIF":6.2,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145749576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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