Far-infrared reflection of (Sr1−x,Cax)(Ga1/2,Ta1/2)O3 ceramics

Far-infra-red reflectivity for Sr(Ga1/2,Ta1/2)O3 and (Sr1−x,Cax)(Ga1/2,Ta1/2)O3 ceramics was observed and effective charges of the ions in their ceramics were calculated in order to investigate the relationship between the effective charges and the dielectric properties in the range of microwave frequencies. These ceramics were prepared by conventional solid phase reaction using high purity reagents. The observed reflectivity spectra were fitted using four infra-red (IR) active modes predicted by factor group analysis in order to estimate the vibration frequencies. The effective charges were calculated from the mode frequencies and the lattice constants. The relationship between the effective charges and Qf values was discussed to find the causes of dielectric loss of (Sr1-x,Cax)(Ga1/2,Ta1/2)O3 ceramics.