Effect of sintering process on microstructure characteristics of Ba(Mg1/3Ta2/3)O-3 ceramics and their microwave dielectric properties

Microstructure of Ba(Mg1/3Ta2/3)O-3, BMT, materials were examined using transmission electron microscopy. Selected area electron diffractions imply that the ordering of Mg2+ and Nb5+ cations transforms the BMT materials from cubic symmetry to P (3) over bar m1 symmetry, which induces the formation of polar domains in BMT grains. Large grains contain wavy polar domain boundaries, dislocations and even the dislocation networks, which are detrimental to the microwave dielectric properties. Presumably, induction of abundant defects in association with large BMT grains is the prime factor degrading the microwave dielectric properties of the BMT materials, when they were sintered at too high temperature. (C) 2001 Published by Elsevier Science Ltd. All rights reserved.