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, τf = −30 ppm/K and high Q × f values, which increased from ∼68,000 GHz at x = 0 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 × f values.