Effect of preparation conditions on cation ordering and dielectric properties of Ba(Mg1/3Ta2/3)O3 ceramics

The effect of preparation conditions on cation ordering and dielectric properties of Ba(Mg1/3Ta2/3)O3 ceramics was investigated. Preparation of Ba(Mg1/3Ta2/3)O3 by conventional synthesis from BaCO3, MgO, and Ta2O5 was compared to an alternate route of reaction of MgTa2O6 with BaCO3. It was shown that in the conventional synthesis method, intermediate phases inhibit formation of single-phase Ba(Mg1/3Ta2/3)O3 up to 1400 °C, whereas utilization of a MgTa2O6 precursor produces the nearly pure perovskite phase after heat treatment at 1000 °C. In the temperature range of 1400-1620 °C, the Ba(Mg1/3Ta2/3)O3 ceramic remains single phase. Traces of the Ba3Ta5O15 phase were detected by XRD and EDX in samples sintered above 1630 °C. Decrease in the 1:2 cation ordering and increase of dielectric loss were observed in samples sintered at T>1590 °C.