Abstract
? 2022 Elsevier B.V.A new method is proposed to predict the formation of high-entropy single-phase oxide with a pyrochlore structure synthesis from non-equivalent principal elements. Based on this concepte, the La2B2O7 (B = Zn2+, Mg2+/Ni2+, Ce4+/Zr4+/Hf4+/Sn4+/Ti4+, W6+, Mo6+) were designed, in which high-entropy La2(ZnMgZrWMo)2O7, La2(ZnMgHfWMo)2O7 and La2(ZnMgSnWMo)2O7 pyrochlore ceramics were successfully prepared by solid-phase sintering. The microstructure of the entropy-stabilized phase was demonstrated using X-ray diffraction and elemental mapping, and the thermal properties including the thermal expansion coefficient and thermal conductivity were analyzed. The results show that La2(ZnMgZrWMo)2O7 has a higher thermal expansion coefficient (13.9 × 10–6 K–1) and lower thermal conductivity (0.8 W/m·K) than its corresponding single-components compound. In addition, La2B2O7 (B = Zn2+, Mg2+, Zr4+/Hf4+/Sn4+, W6+, Mo6+) pyrochlore high-entropy ceramics exhibit good calcium – magnesium – aluminosilicate (CMAS) resistance, the apatite protective layer generated after the reaction of La with CMAS effectively prevents further corrosion. This study suggests a novel method for predicting the formation of high-entropy single-phase oxides of pyrochlore structures and provides a new design concept for anti-CMAS corrosion materials.
NSTL
Elsevier