Influence of bismuth cations on the synthesis and ordering behavior of lead magnesium niobate and barium magnesium niobate

The behavior of Bi3+ substituted on the A site of MMg1/3Nb2/3O3 (M = Pb2+, Ba2+) is shown to differ drastically from that of La3+. The more restricted isomorphism in the Bi-substituted systems compared to their La analogs is attributable to the fact that the bond strain in the Bi systems reaches the critical level. The lattice parameter of the Bi-substituted magnesium niobates is a very weak function of doping level, no 1 : 1 ordering occurs, their peak-permittivity temperature is a nonmonotonic function of Bi content, and their peak permittivity decreases with increasing Bi content, which is tentatively attributed to the incorporation of Bi in both A and B sites of the perovskite structure