A new mechanism of nonstoichiometric 1 : 1 short-range ordering in Pb(Mg1/3Nb2/3)O-3-based relaxor ferroelectrics

Abstract

A new mechanism of the nonstoichiometric 1:1 short-range ordering leading to the enhanced diffuse phase transition (DPT) was proposed and tested using NiO-doped Pb(Mg1/3Nb2/3)O-3 (PMN) as a model system for Pb(B-1/3'B-1/3")O-3-type relaxer ferroelectrics. Both the enhanced DPT and the increase in the intensity of the superlattice reflection were observed in the presence of NiO. These observations were interpreted in terms of the increase in the number density of the short-range ordered nanodomains without the domain growth. It was shown that the substitution of Ni2+ ions for Nb5+.ions in the B-site sublattice of perovskite PMN produced the negatively charged Ni-Nb''' sites with a concomitant generation of oxygen vacancies (V-O(..)) for the ionic charge compensation. This defect process stabilizes the newly formed nonstoichiometric 1:1 short-range ordered domains and, thus, increases the number density of the ordered nanodomains in a disordered matrix.