Formation of single-phase multicomponent zirconate with colossal atomic radius difference via reactive flash sintering

In this study, multicomponent rare-earth zirconate ceramics (Sm_0.2Eu_0.2Tb_0.2Dy_0.2Lu_0.2)₂Zr₂O₇ and (La_0.2Eu_0.2Gd_0.2Yb_0.2Y_0.2)₂Zr₂O₇ were synthesized via conventional sintering and reactive flash sintering, respectively. Single-phase (Sm_0.2Eu_0.2Tb_0.2Dy_0.2Lu_0.2)₂Zr₂O₇ ceramics, with the defect fluorite structure, were successfully obtained via conventional sintering and reactive flash sintering, while secondary phase segregation and precipitation were observed only in conventionally-sintered (La_0.2Eu_0.2Gd_0.2Yb_0.2Y_0.2)₂Zr₂O₇ ceramics. This study proposes that the critical electric field of reactive flash sintering introduces defects to soften the lattice, which not only improves the mass transportation, but also relieves the lattice stress induced by the atomic radius difference, resulting in the single-phase defect fluorite structure of (La_0.2Eu_0.2Gd_0.2Yb_0.2Y_0.2)₂Zr₂O₇. Thus, reactive flash sintering is an efficient route for synthesizing and developing novel multicomponent oxides that cannot be synthesized via conventional sintering due to pronounced lattice stress.