1 : 2 Long-range ordering and defect mechanism of WO3-doped perovskite Ba(Mg1/3Ta2/3)O3

The nature of the B-site cation ordering and the associated defect process necessary to stabilize the ordered domains were investigated using the WO3-doped Ba〈Mg1/3Ta2/3〉O3 〈BMT〉 system as a typical example of Ba〈B′1/3B″2/3〉O3-type complex perovskites. It was shown that only the 1 : 2 long-range ordering of the B-site cation existed in both undoped and WO3-doped BMT perovskites. The atomic defect mechanism associated with the stoichiometric 1 : 2 long-range ordering was systematically investigated. It is concluded that the substitution of W6+ for Ta5+ in the WO3-doped BMT enhances the degree of the 1 : 2 long-range ordering and produces the positively charged W Ta ⋅ sites with a concomitant generation of tantalum vacancies 〈VTa″″′〉 and mobile oxygen vacancies 〈V⋅⋅ O〉 for the ionic charge compensation.