Microstructure and microwave dielectric characteristics of (1 − x)Ba(Zn1/3Ta2/3)O3–xBaTi4O9 ceramics

(1 − x)Ba(Zn1/3Ta2/3)O3–xBaTi4O9 (0.1 ≤ x ≤ 0.85) composites are prepared by mixing 1150 °C-calcined BaTi4O9 with 1150 °C-calcined Ba(Zn1/3Ta2/3)O3 powders. The crystal structure, microwave dielectric properties and sinterabilites of the (1 − x)Ba(Zn1/3Ta2/3)O3–xBaTi4O9 ceramics have been investigated. X-ray diffraction patterns reveal that BaTi4O9, ordered and disordered Ba(Zn1/3Ta2/3)O3 phases exist independently over the whole compositional range. The sintering temperatures of (1 − x)Ba(Zn1/3Ta2/3)O3–xBaTi4O9 ceramics are about 1240 – 1320 °C and obviously lower than those of Ba(Zn1/3Ta2/3)O3 ceramics. The dielectric constants (ɛr) and the temperature coefficient of resonant frequency (τf) of (1 − x)Ba(Zn1/3Ta2/3)O3–xBaTi4O9 ceramics increase with the increase of BaTi4O9 content. Nevertheless, the bulk densities and the quality values (Q × f) of (1 − x)Ba(Zn1/3Ta2/3)O3–xBaTi4O9 ceramics increase with the increase of Ba(Zn1/3Ta2/3)O3 content. The results are attributed to the higher density and quality value of Ba(Zn1/3Ta2/3)O3 ceramics, the better grain growth, and the densification of sintered specimens added a small BaTi4O9 content. The (1 − x)Ba(Zn1/3Ta2/3)O3–xBaTi4O9 ceramic with x = 0.1 sintered at 1320 °C exhibits a ɛr value of 31.5, a maximum Q × f value of 68500 GHz and a minimum τf value of 4.1 ppm/°C.