Ab initio study of Pb antisite defects in PbZrO3 and Pb(Zr,Ti)O3

We report an ab initio study of Pb antisite defects in PbZrO3 (PZ) and Pb(Zr,Ti)O-3 (PZT) perovskites. Also, we calculated the enthalpy of formation of PZ. Our results show that, under strong oxidizing conditions, Pb on the Zr-site antisite defects are unavoidable in PZ. Moreover, a positive enthalpy of formation (0.15 eV) of PZ is found. This indicates that PZ is metastable for low temperature and may help explain the difficulty in synthesizing high-quality Zr-rich PZT crystals. The Pb antisite defects in PZT alloys have low formation energies. This result is in agreement with experiments, which report the predominance of this defect in PZT films. We find that the Pb antisite defect produces electron traps 0.2-0.8 eV below the conduction-band edge.