Dependence of the octahedral bond valence on microwave dielectric properties of Ca1−xSm2x/3TiO3 ceramics

Microwave dielectric properties of Ca1−xSm2x/3TiO3 ceramics were investigated as a function of Sm3+ contents (0≤x≤0.6). In the entire composition range, the perovskite single phase was detected. With the increasing Sm3+ content, Q·f (Q=1/tan δ) value increased, however dielectric constant (K) decreased. As Sm3+ content increased, the deviation between the observed dielectric polarizabilities (αobs) and the theoretical ones (αtheo) decreased with increasing bond valence in octahedral site due to the decreasing unit-cell volume. The temperature coefficients of the resonant frequencies (TCF) of the specimens were dependent on the bond valence of octahedral site.