CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Yian Chen,Tingting Xuan,Xiaohui Li,Ting Liu,Bo Wu,Yuling Tuo,Xiaoyi Chen,Bo Gao
In this study, a series of high-entropy rare-earth zirconate (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 A 0.2 ) 2 Zr 2 O 7 (A = Dy, Ho, or Er) ceramics containing five principal elements were synthesized via the high-temperature solid-state method, and their potential as high-temperature thermosensitive ceramics was investigated. X-ray diffraction and Raman spectroscopy confirmed the single-phase pyrochlore structural characteristics of these ceramics, while scanning electron microscopy revealed a dense microstructure. Electrical measurements demonstrated that these ceramics are capable of operating at temperatures up to 1500 °C and exhibiting exceptional sensitivity within the 400–1500 °C range, both of which are attributed to their high resistivity at elevated temperatures and a large material constant B value (≥11,241 K) across the entire operating temperature span. Notably, (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 A 0.2 ) 2 Zr 2 O 7 (A = Dy, Ho, or Er) ceramics also maintained a resistivity drift rate of ≤0.53 % after 500 h of continuous exposure at 1500 °C, a result ascribed to the high-entropy effect suppressing lattice distortion, as evidenced by ab initio molecular dynamics simulations. These findings validate the high-entropy strategy as a promising approach for developing durable, high-performance NTC thermistors for extreme-temperature applications.
研究领域:
材料科学
·
无机非金属材料
·
传感器技术
✓ 已验证
产品关联
DOI
高影响因子
NUCLEAR ENGINEERING AND DESIGN
·
2024
·
IF 1.9
Shiyin Ji,Xiuhua Ji,Yanhao Song,Yanxia Wei,Tao Duan
Regulation of microstructure and processing cost of waste form are important for the design and application of high-level radioactive waste immobilization. In this study, CaZrTi 2 O 7 (zirconolite) – CaNdTiNbO 7 (pyrochlore) ceramics were synthesized via conventional sintering method at 1000–1500 °C to investigate the effect of sintering temperature on the microstructure, solidification, and crystal evolution. The powder x-ray diffraction (XRD) and backscattered scanning electron microscopy–energy dispersive spectroscopy (BSEM–EDS) results indicated gradual formation of zirconolite and pyrochlore ceramics, following with their densification when increasing sintering temperature. It was found that sintering temperature should be higher than 1300 °C to form zirconolite-pyrochlore solid solutions. Densified pyrochlore was obtained at 1500 °C. In addition, transformation from relatively low-symmetry lattice to higher-symmetry lattice was found with an increase in sintering temperature. Furthermore, higher temperature can enhance the crystal growth and densification in the ceramic composite. The finding in this study could provide important suggestions to design and process zirconolite-pyrochlore waste forms for industrial application.
研究领域:
材料科学
·
核能工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2025
·Vol. 108
·期 8
·e20574
·
IF 3.8
Ruifeng Wu,Yafei Liu,Hao Sun,Jianan Xu,Jia Chen,Aimin Chang,Bo Zhang
Tungsten-bronze materials are widely used in the fields of electro-optic, photorefractive, pyroelectric, millimeter-wave, and piezoelectric devices. In particular, tungsten-bronze Ba 4.5 Sm 9 Ti 18 O 54 is believed to be useful for fabricating high-temperature thermistors owing to its semiconductor properties. However, inherent shortcomings such as poor linearity (electrical properties deviate from the Arrhenius equation) and high aging coefficients limit the practical applications of these materials. Incorporating rare-earth ( Re ) ions is an effective means of improving the electrical properties of thermistor materials. In this study, we explore the phase composition and thermosensitive properties of Ba 4.5 Re 9 Ti 18 O 54 (Re = Y, La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Lu) ceramics with tungsten–bronze structures. The results indicate that the tungsten–bronze phase (Ba 4.5 Re 9 Ti 18 O 54 ) is generated when the radius of the Re 3+ ion exceeds 1.04 Å and the tolerance factor surpasses 0.82. Conversely, a pyrochlore phase (Re 2 Ti 2 O 7 ) accompanied by a monoclinic impurity phase (BaTi 2 O 5 ), is formed. Moreover, all Ba 4.5 Re 9 Ti 18 O 54 ceramics with a tungsten-bronze structure exhibit exceptional linear electrical properties ( R 2 ≥ 999.09‰) and high sensitivity coefficients ( α 1000°C ≥ −0.79%/K). In particular, after aging at 1100°C for 600 h, both the aging coefficient and drift rate of material constant are as low as 5.76% and 1.79%, respectively. These results indicate that Ba 4.5 Re 9 Ti 18 O 54 ceramics are promising for high-temperature and high-accuracy temperature measurements.
研究领域:
材料科学
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陶瓷
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固体物理
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热敏电阻技术
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稀土材料
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Dongsheng Jiang,Yuzhe Li,Chao Zhang,Ruifang Wang,Jinpeng Zhu,Wen Chen,Yusi Che,Jilin He
Bayan Obo tailings are rich in niobium and other valuable elements; however, the phase evolution of niobium-bearing slag within these tailings remains poorly understood. This knowledge gap significantly impedes comprehensive utilization of these strategic resources. In this study, a CaO-SiO 2 -Nb 2 O 5 -5%Na 2 O-5%Al 2 O 3 -3%CaF 2 slag system was investigated to examine the phase equilibrium types, compositional characteristics, and distributional evolution under varying w (CaO)/ w (SiO 2 ) ratios and w (Nb 2 O 5 ) contents, using high-temperature equilibrium experiments. Following a 24-hour high-temperature equilibrium treatment at 1473 K under an argon atmosphere, a range of compounds including 13CaO·8SiO 2 ·Nb 2 O 5 ·CaF 2 , 2CaO·4SiO 2 ·Na 2 O·Al 2 O 3 , CaO·Nb 2 O 5 ·NaF, 2CaO·Nb 2 O 5 , and CaO·SiO 2 were identified. An increase in Nb 2 O 5 content coupled with a reduction in the w (CaO)/ w (SiO 2 ) ratio favored the formation of CaO·Nb 2 O 5 ·NaF (pyrochlore phase) and 2CaO·Nb 2 O 5 . These two phases exhibited high Nb concentrations, with the CaO·Nb 2 O 5 ·NaF (pyrochlore) phase containing up to approximately 70% Nb. The optimal smelting conditions for niobium enrichment in the pyrochlore phase were identified within the range of w (CaO)/ w (SiO 2 ) = 0.74∼0.80 and w (Nb 2 O 5 ) = 13.61%∼16.11%.
研究领域:
冶金学
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材料科学
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矿物加工
·
物理化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2025
·Vol. 108
·期 9
·e20693
·
IF 3.8
Yanhao Song,Xiuhua Ji,Kui Tang,Yihao Zhang,Tongshen Xu,Shiyin Ji,Tao Duan
Zirconolite and pyrochlore are recognized as the promising candidates for HLW immobilization because of their excellent chemical durability, radiation resistance and so on. In this study, the nominal CaZr 1- x Sm x Ti 2- x Nb x O 7 ( x = 0.1–1.0) compounds were synthesized to explore their microstructure, phase evolution and chemical durability. The X-ray diffraction (XRD), back-scattered scanning electron microscopy with energy dispersive X-Ray spectrometry (BSEM-EDS) and Raman analysis results displayed that the phase transformation was two-layer to four-layer monoclinic zirconolite (2M to 4M) and then to cubic pyrochlore with concentration of Sm 3+ and Nb 5+ raising. The crystalline structure evolution of 2M to 4M zirconolite and zirconolite-4M to cubic pyrochlore were determined firstly at x = 0.2 and x = 0.3 sample, respectively. Zirconolite-4M with trace perovskite was prepared at x = 0.2 sample. Near single-phase pyrochlore would be obtained when x ≥ 0.4. Moreover, the chemical durability of zirconolite-4M was stronger than zirconolite-2M and the composite of zirconolite-4M and pyrochlore. The findings could be helpful for the design of zirconolite-based waste forms for actinides such as Np 3+ , Am 3+ , and others.
研究领域:
材料科学
·
核废物处理
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无机非金属材料
·
固态化学
·
放射化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2025
·
IF 6.2
Sihao Wang,Xiaoling Zhang,Yanghai Zheng,Yun Xue,Jingping Wang,Yongde Yan
Zinc Titanate (ZIT) glass-ceramic matrix is a promising candidate for immobilizing radioactive Eu element based on the reactions between Eu and raw material of Zn 2 TiO 4 /CaHPO 4 . However, the generated Eu 2 Ti 2 O 7 ceramic with unstable fluorite defect structure hampers the mechanical properties and chemical durability of ZIT-Eu (ZIT glass-ceramic waste form immobilized with Eu 2 O 3 ). This study addresses the issue by developing the Ce-doping ZIT-Eu waste forms using a solid-phase sintering method at high temperature, realizing the conversion from unstable defective fluorite to stable pyrochlore. As evidenced by the experimental measurements, the density, hardness, water absorption and chemical stability are significantly improved after Ce doping, with the 6 wt% Ce exhibiting the best aqueous durability, retaining a leach value of only 0.11 × 10 −9 g·m −2 ·d −1 at 90 ℃ after 28 days. Furthermore, the density functional theory calculation reveals the potential mechanism that Ce doping decreases the adsorption capability for H 2 O and increases the lattice energy for Eu ion diffusion. In conclusion, this simple doping strategy promotes the application of ZIT glass-ceramic matrix in the field of radioactive waste treatment.
研究领域:
核废物固定
·
材料科学
·
固态化学
·
放射化学
·
陶瓷材料
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2025
·Vol. 46
·期 2
·117844
·
IF 6.2
Zhuangzhuang Ma,Yunhao Wang,Tianhao Rui,Yulin Lan,Linyuan Lu,Yang Yu,Mingxuan Deng,Tianxing Lan,Zhekang Zhao,Zhen Teng,Haibin Zhang
High-entropy pyrochlore ceramics with the nominal composition Eu 2 B 2 O 7 , incorporating up to five equiatomic B-site cations, were synthesized via a solid-state reaction method and evaluated their aqueous chemical durability for nuclear waste immobilization. Comprehensive characterization using XRD, Raman, and SEM analyses confirmed the formation of a single-phase pyrochlore structure with uniform and random elemental distribution. However, secondary phases were observed in the Ce- and Nb-doped samples, which is attributed to the larger ionic radius of Ce and the higher valence state of Nb. The 42 days leaching tests revealed normalized element release rates ranging from 10 −5 to 10 −7 g/(m 2 ∙d), significantly lower than those of conventional pyrochlore materials. This enhanced durability is attributed to synergistic effects of electronegativity, ionic radius, and atomic number, which together hinder cation diffusion and strengthen chemical durability at the B site. These findings demonstrate the potential of Eu 2 B 2 O 7 high-entropy pyrochlore ceramics as long-term host materials for high-level radioactive waste. This study provides a valuable resource for enriching the thermophysical properties database of B-site high-entropy pyrochlore solidification, thereby supporting their engineering development.
研究领域:
材料科学
·
核化学
·
无机非金属材料
·
放射性废物处理
·
固体化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry A
·
2025
·
IF 9.5
Hao Sun,Ruifeng Wu,Yafei Liu,Jia Chen,Jianan Xu,Xia Huang,Aimin Chang,Bo Zhang
Precise temperature sensing in extreme high-temperature environments, such as those encountered in energy and aerospace applications, demands high-performance thermosensitive materials, among which fergusonite-type oxide ceramics are prominent candidates. However, due to the complicated local structural design, simultaneously achieving rapid response/recovery, high sensitivity and accuracy under high-temperature conditions remains a challenge. Herein, second-phase precipitation (cubic CeO2) and B-site modulation were introduced in CaCe2Nb2−xTaxMoO12 ceramics by regulating solid solubility and sintering protocols. Synergistic optimization of grain boundaries and defect structure enabled carrier migration channels and precise thermal activation control. Exceptional temperature sensitivity and measurement accuracy were achieved over a broad temperature range (153–773 K), with a rapid response time of 1.82 s and recovery time of 0.76 s at 773 K. Notably, these ceramics demonstrate remarkable stability during thermal cycling and prolonged high-temperature operation. This work presents new material candidates and multiscale regulation strategies for developing high-temperature thermosensitive materials surpassing conventional ceramic systems.
研究领域:
材料科学
·
无机非金属材料
·
功能陶瓷
·
传感器件
·
高温材料工程
✓ 已验证
产品关联
DOI
高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2023
·Vol. 25
·期 40
·27045-27052
·
IF 3.3
Junwei Xu,Xusheng Zhong,Rumeng Ouyang,Ying Gong,Yameng Liu,Xianglan Xu,Xiuzhong Fang,Xiang Wang
To elucidate the effect of the A2B2O7 phase on the oxidative coupling of methane (OCM) while excluding elemental influences, La2Zr2O7 compounds with a disordered defect fluorite (La2Zr2O7-F) structure and an ordered pyrochlore phase (La2Zr2O7-P) have been synthesized. Irrespective of their element composition, the catalytic performance of La2Zr2O7-F exceeds that of La2Zr2O7-P. Furthermore, the La2Zr2O7-F surface has more oxygen vacancies/defects than the La2Zr2O7 surface because La2Zr2O7-F exhibits a higher lattice disorder degree and lower B–O bond strength, which leads to the formation of more reactive oxygen anions (O2− and O22−) and basic sites for OCM. Isotopic exchange results have testified that surface-active oxygen sites are generated due to the gaseous O2 adsorption/activation occurring on the surface vacancies via both simple and multiple hetero-exchange mechanisms. In conclusion, crystal structure is the primary factor that governs the catalytic performance of A2B2O7 compounds, with the disordered defect fluorite phase being the most optimal structure for OCM.
研究领域:
催化
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Shuo Huang,Ying Hong,Liye Ding,Kaiyun Li,Haoliang Yuan,Ziang Luo,Shijia Li,Sheng Zhang,Chunhui Xu,Hongyun Jin
High-entropy ceramics have recently emerged as promising candidates for advanced thermal-barrier-coating applications due to their exceptional tunability and thermal stability. In this work, the phase stability, elastic behavior and thermal performance of a non-equimolar high-entropy zirconate (Nd 0.4 Ce 0.15 Sm 0.15 Eu 0.15 Yb 0.15 ) 2 Zr 2 O 7 are systematically investigated through ab initio calculations based on the special quasi-random structure approach, and validated by complementary experimental characterizations. The material preferentially crystallizes into a pyrochlore-type structure, with sharp diffraction peaks and uniform elemental distribution confirming its crystallinity and compositional homogeneity. The elastic behavior is analyzed by single-crystal and polycrystalline elastic moduli using a series of phenomenological models. The broad distribution of metal-nonmetal bond lengths highlights large distortion fluctuations, which strongly influence the intrinsic materials parameters. The material exhibits high Vickers hardness (18.2 GPa) and thermal expansion coefficient (11.77 × 10 -6 K -1 at 1773 K), exceeding that of pristine Nd 2 Zr 2 O 7 and conventional yttria-stabilized zirconia. Additionally, the severe lattice distortion induces strong phonon scattering, resulting in low thermal conductivity (1.16 W⋅m -1 ⋅K -1 at 1773 K). The integrated theoretical-experimental study provides critical insights for the rational design of high-entropy materials for extreme-temperature applications.
研究领域:
材料科学
·
陶瓷学
·
热障涂层
·
计算材料物理
·
固态化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF SOLID STATE CHEMISTRY
·
2025
·
IF 3.5
Xiaohui Li,Pengjun Zhao,Wenwen Kong,Aimin Chang,Bo Gao
Understanding electrical transport mechanisms and key thermal stability factors in high-temperature thermosensitive ceramics is essential for developing highly stable temperature sensors under extreme thermal conditions. This study develops the high-entropy pyrochlore stannates (La 0.2 Nd 0.2 Sm 0.2 Gd 0.2 M 0.2 ) 2 Sn 2 O 7 (M = Eu, Dy, Ho, or Yb) via solid-state synthesis, demonstrating exceptional negative temperature coefficient (NTC) behavior across 300 – 1400 °C. Hall measurements and X-ray photoelectron spectroscopy (XPS) analyses reveal a dual redox mechanism for these ceramics: partial reduction of Sn 4+ to Sn 2+ at B-sites and rare-earth ions (Sm/Eu/Yb) to RE 2+ at A-sites, generating hole-dominated p-type conductivity. The materials exhibit outstanding thermal stability, with resistance drift below 1.96% after 500 hours at 1400 °C, attributed to the entropy-stabilized structure that effectively suppresses lattice disorder transformation. Aging studies further demonstrate that high oxygen vacancy concentrations lead to resistance drifts, as oxygen filling at elevated temperatures oxidizes RE 2+ to RE 3+ , reducing charge carriers and ultimately increasing resistivity. This study elucidates for the first time the hole-dominated conduction mechanism arising from dual-site cation valence changes (Sn/RE) and the regulation effect of oxygen vacancies on high-temperature stability, which provides an important theoretical basis and material design strategy for the development of the next-generation high-temperature NTC sensors with excellent stability.
研究领域:
材料科学
·
陶瓷材料
·
电气工程
·
固态物理
·
热传感器
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）