Preparation and phase evolution of high-entropy oxides A2B2O7 with multiple elements at A and B sites

By Zhen Teng, Y. Tan, Sifan Zeng, Yan Meng, Chen Chen, Xiaochun Han, Haibin Zhang. 2021

162 citations recorded by the source corpus.

Abstract In this study, 37 kinds of high-entropy pyrochlore/fluorite ceramics with equiatomic multicomponent compositions were successfully synthesized and the process of phase transformation was also investigated. Eventually, the experimental results show that 33 among the high-entropy compounds exhibit a single pyrochlore/fluorite structure with all cations randomly and uniformly distributed at A and B sites. Meanwhile, the ionic radii, valence, and size disorder may be the main driving forces for the formation of single-phase high-entropy pyrochlore/fluorite oxides. Furtherly, the average radius ratio(rA/rB) is the main factor of the pyrochlore/fluorite phase transformation. And when the average radius ratio(rA/rB) extends from 1.46 to 1.78, the high-entropy pyrochlore structure is stable. When the average radius ratio rA/rB is less than 1.46, it transforms into the defective fluorite structure. This study not only further expands the high-entropy pyrochlore family and but also is expected to guide the design of high-entropy pyrochlore through composition customization.

Subfields: Materials Chemistry, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/e0463d08f2c46310b164f7ce86407487e7ca320b