High-temperature elemental segregation induced structure degradation in high-entropy fluorite oxide  

作　　者：Yixuan Hu Mariappan Anandkumar Yumeng Zhang Joydip Joardar Atul Suresh Deshpande Xiaodong Wang Kolan Madhav Reddy 

机构地区：[1]School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240,China [2]Department of Materials Science and Metallurgical Engineering,Indian Institute of Technology Hyderabad,Sangareddy 502285,India [3]International Advanced Research Centre for Powder Metallurgy and New Materials(ARCI),Hyderabad 500005,India

出　　处：《Journal of Advanced Ceramics》2024年第3期310-322,共13页先进陶瓷（英文）

基　　金：This work was supported by the National Natural Science Foundation of China(Grant Nos.52150610487 and 51850410501).The authors acknowledge the help of Dr.Linlin Ma for UV-Vis spectra from the Instrumental Analytical Center of Shanghai Jiao Tong University.

摘　　要：Fluorite-structured oxides constitute an important category of oxides with a wide range of high-temperature applications.Following the concept of high entropy,high-entropy fluorite oxides(HEFOs)have showcased intriguing high-temperature application potential.However,unlocking this potential necessitates an assessment of their long-term stability under high-temperature conditions.In this study,we conducted a prolonged heat treatment at 1000℃on typical HEFO,specifically(CeHfZrGdLa)O_(x).After 100 h,high-intensity X-ray diffraction(XRD)revealed a transition from a single-phase fluorite to a multi-phase configuration.Further investigation by analytical electron microscoy(AEM)demonstrated that this degradation resulted from facilitated element diffusion and consequent escalating chemical fluctuation at high temperatures,leading to spontaneous segregation and separation of Ce and La elements,forming Ce-rich,La-poor,and La-rich phases.Notably,the La-rich phase spontaneously transformed from a fluorite structure(space group Fm3m)to a bixbyite structure(space group Ia3)at elevated temperatures,resulting in the appearance of superstructure reflection in XRD profiles and electron diffraction patterns.Despite the intricate phase decomposition,the energy band gap showed minimal variation,suggesting potential property stability of(CeHfZrGdLa)O_(x)across a broad range of compositions.These findings offer valuable insights into the future applications of HEFOs.

关 键 词：phase transition high-temperature stability elemental segregation high-entropy fluorite oxides(HEFOs) 

分 类 号：TQ174.1[化学工程—陶瓷工业]