The dielectric and electric properties of (Ba0.68-xSr0.311Bi0.006Mgx)(Ti0.99Sn0.01)O3 ceramics

(Ba0.68-xSr0.311Bi0.006Mgx)(Ti0.99Sn0.01)O-3 ceramics were prepared by conventional solid state reaction method. The influences of Mg2+ content on structure, dielectric and electric properties of the sintered specimens were investigated. At lower Mg2+ concentrations (x <= 0.015), Mg2+ replaced Bi3+ at the A-site in the perovskite structure, which made dielectric constant to obey the Curie-Weiss law above the phase transition temperature. The Bi3+ expelled from the lattice by Mg2+ were concentrated at grain surfaces, which caused significant decrease in grain size and epsilon(max). At higher Mg2+ concentrations (x > 0.015), Mg2+ acted as an acceptor dopant to replace Ti4+ at the B-site of the perovskite structure, leading to a deformation of the cubic lattice and making dielectric behavior to deviate from the Curie-Weiss law above the phase transition temperature. In high temperature region, the conduction carriers of all samples were controlled by V-o(center dot center dot). (C) 2010 Elsevier B.V. All rights reserved.