Relationships between Sr substitution for Ba and dielectric characteristics in Sm2BaZnO5 ceramics

The effects of Sr substitution for Ba in Sm-2(Ba1-xSrx)ZnO5 solid solutions on the crystal structure and microwave dielectric properties were investigated in this study. The epsilon(r) values of Sm-2(Ba1-xSrx)ZnO5 are slightly increased with increasing x in the range 0 less than or equal to x less than or equal to 0.1, and the Q(.)f values are extremely decreased from 35505 to 8522 GHz. The variations in the Q(.)f values may depend on the differences in the crystal structure because a single phase of Sm-2(Ba1-xSrx)ZnO5 with tetragonal structure was produced for x greater than or equal to 0.1 compositions instead of an orthorhombic structure. The highest Q(.)f value in Sm-2(Ba1-xSrx)ZnO5 with a tetragonal structure was 19283 GHz at x = 1. The increase in the Q(.)f values of samples with x greater than or equal to 0.1 were attributed to the grain growth induced by the Sr substitution for Ba. In the sample at x = 1 many microcracks were observed. In order to remove these cracks, Co was substituted for Zn in Sm2SrZnO5, which improved the Q(.)f values. (C) 2003 Elsevier Ltd. All rights reserved.