Influence of average radii of RE3+ ions on phase structures and thermal expansion coefficients of high-entropy pyrosilicates  

作　　者：Zeyu Chen Chucheng Lin Wei Zheng Xuemei Song Caifen Jiang Yaran Niu Yi Zeng 

机构地区：[1]State Key Lab of High Performance Ceramics and Superfine Microstructure,Shanghai Institute of Ceramics,Chinese Academy of Sciences,Shanghai 200050,China [2]Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China [3]Key Laboratory of Inorganic Coating Materials CAS,Shanghai Institute of Ceramics,Chinese Academy of Sciences,Shanghai 200050,China

出　　处：《Journal of Advanced Ceramics》2023年第5期1090-1104,共15页先进陶瓷（英文）

基　　金：supported by the Instrument and Equipment Development,Chinese Academy of Sciences(YJKYYQ20210030);Shanghai Science and Technology Innovation Action Plan(21142201100).

摘　　要：High-entropy pyrosilicate element selection is relatively blind, and the thermal expansion coefficient (CTE) of traditional β-type pyrosilicate is not adjustable, making it difficult to meet the requirements of various types of ceramic matrix composites (CMCs). The following study aimed to develop a universal rule for high-entropy pyrosilicate element selection and to achieve directional control of the thermal expansion coefficient of high-entropy pyrosilicate. The current study investigates a high-entropy design method for obtaining pyrosilicates with stable β-phase and γ-phase by introducing various rare-earth (RE) cations. The solid-phase method was used to create 12 different types of high-entropy pyrosilicates with 4–6 components. The high-entropy pyrosilicates gradually transformed from β-phase to γ-phase with an increase in the average radius of RE^(3+) ions ( r¯(RE^(3+))). The nine pyrosilicates with a small r¯(RE^(3+)) preserve β-phase or γ-phase stability at room temperature to the maximum of 1400 ℃. The intrinsic relationship between the thermal expansion coefficient, phase structure, and RE–O bond length has also been found. This study provides the theoretical background for designing high-entropy pyrosilicates from the perspective of r¯(RE^(3+)). The theoretical guidance makes it easier to synthesize high-entropy pyrosilicates with stable β-phase or γ-phase for the use in environmental barrier coatings (EBCs). The thermal expansion coefficient of γ-type high-entropy pyrosilicate can be altered through component design to match various types of CMCs.

关 键 词：environmental barrier coatings(EBCs) high-entropy pyrosilicates phase structure thermal expansion coefficient(CTE) 

分 类 号：TQ174.1[化学工程—陶瓷工业]