The B-site cation ordering and associated defect processes in WO3-doped Ba(Mg1/3Ta2/3)O-3

Abstract

The nature of the cation ordering and the defect process necessary to stabilize the ordered regions in the WO3-doped Ba(Mg1/3Ta2/3)O-3 (BMT) were investigated. From the TEM observation, it was shown that only the stoichiometric 1:2 ordering of the B-site cation existed in both the WO3-doped and the undoped BMT. The substitution of W ion for Ta ion enhanced the degree of the stoichiometric 1:2 ordering, and this observation can be interpreted in terms of the increase in the coulombic interaction between the neighboring B-site cations. Analysis of the electrical conductivity indicates that the undoped BMT is a p-type conductor and that the substitution of W6+ for Ta5+ in the WO3-doped BMT produces positively charged W-Ta sites with a concomitant generation of tantalum vacancies and oxygen vacancies. This defect process stabilizes the ordered macrodomains.