Five Ba(Co1/3Nb2/3)O3 samples sintered at different temperatures (form 1350 to 1550 °C), one Ba(Mg1/3Ta2/3)O3 and a Ba(Mg1/3Nb2/3)O3 sample were examined by Raman scattering to reveal the correlation of the 1:2 ordered perovskite structure with the microwave properties, such as dielectric constant and Q factors. The Ba(Co1/3Nb2/3)O3 sample sintered at 1400 °C, which possesses the highest microwave Q value and the lowest dielectric constant among five Ba(Co1/3Nb2/3)O3 samples, has the narrowest width and the highest frequency of the stretch mode of oxygen octahedron (i.e. A1g(O) near 800 cm−1). We found that the dielectric constant is strongly correlated with the Raman shift of A1g(O) stretch modes, and the width of A1g(O) stretch mode reflects the quality factor Q × f value in the 1:2 ordered perovskite materials. This concludes that the oxygen octahedron play an important role of the material's microwave performance. Based on the results of Q × f values and the lineshapes of A1g(O) stretch mode, we found that the propagation of microwave energy in Ba(Mg1/3Ta2/3)O3 and Ba(Mg1/3Nb2/3)O3 shows weak damping behavior, however, Ba(Co1/3Nb2/3)O3 samples sintered at different temperature exhibit heavily damped behavior.
Journal of the European Ceramic Society 26(10-11), pp.1965-1968