Effect of Ta2O5 on Microstructure and Microwave Dielectric Properties of Ba(Zn1/3Ta2/3)O3 Ceramics

Abstract

When Ta2O5 was added to Ba(Zn1/3Ta2/3)O3 (BZT) ceramics, the degree of the 1:2 ordering increased and the Ba3Ta5O15 second phase was formed. Grain growth and liquid phase were also found in Ta2O5 added BZT ceramics sintered above 1580°C. The liquid phase, which is responsible for grain growth, is related to the Ba3Ta5O15 second phase. The Q-value of BZT ceramics sintered above 1580°C was considerably increased with the addition of a small amount of Ta2O5. Since the relative density decreased with the addition of Ta2O5, the increase of the Q-value is not related to the relative density. In contrast, the improvement of the Q-value could be explained by the increase in the grain size because the average grain size increased with the addition of Ta2O5. When a large amount of Ta2O5 was added, however, the Q-value became very low even though the grain size was very large. The low Q-value might be attributed to the low relative density and the presence of a large amount of the Ba3Ta5O15 second phase.