Study of High-Temperature Stability of Pyrochlore Zirconates

Based on defect chemistry theory and molecular dynamics, the defect formation energy and its relationship with the mechanism of pyrochlore-fluorite phase change were investigated, so as to reveal the underlying mechanism of high-temperature stability of pyrochlore zirconates. Results showed that with the rise of the atom mass of A, the defect formation energies decreased that meant the crystal structure tended to become more disordered. Noticeably, the first nearest cation antisite dominated the pyrochlore disorder transformation process. In addition, it was found that the diffusion of oxygen atoms was far higher than that of cations, and was increased with the temperature, thus also promoting the pyrochlore-fluorite transformation process.