The homogeneity range and the microwave dielectric properties of the BaZn2Ti4O11 ceramics

Ceramics with a composition close to BaZn2Ti4O11 were synthesized according to various substitutional mechanisms in order to verify an existence of a homogeneity range in the vicinity of this composition. Structural and microstructural investigations showed that the crystal structure of BaZn2Ti4O11 was formed in the homogeneity range corresponding to the formula BaZn2-xTi4O11-x (0 < x < 0.1). Densely sintered BaZn2-xTi4O11-x (0 < x < 0.1) ceramics exhibited a dielectric constant around 30, tau(f) = -30ppm/K and high Q x f values, which increased from similar to 68,000GHz at x = 0 to similar to 83,000 GHz at x = 0.05. Structurally, the deficiency of Zn in BaZn2-xTi4O11-x (0 < x < 0.1) resulted in a slight decrease in the unit-cell volume. The influence of secondary phases in the BaZn2Ti4O11-based materials on the microwave dielectric properties was also investigated. A presence of small amounts of ZnO, BaTiO3, hollandite-type solid solutions (BaxZnxTi8-xO16) and BaTi4O9 caused a decrease in Q x f values. (c) 2006 Elsevier Ltd. All rights reserved.