Effects of Sm ³⁺ Substitution on Dielectric Properties of Ca _{1− <i>x</i>} Sm _{2 <i>x</i> /3} TiO ₃ Ceramics at Microwave Frequencies

Abstract

Microwave dielectric properties of Ca 1‐ x Sm 2 x /3 TiO 3 ceramics were investigated as a function of the amount of Sm 3+ substitution (0.0 ≤ x ≤ 0.8). The structure was changed from orthorhombic perovskite at x = 0.0 to tetragonal at x = 0.6. As the calcium vacancy concentration increased with increased Sm 3+ substitution, the unloaded Q value (similar/congruent 1/tan delta) increased up to the solid‐solution limit at x = 0.6 and then decreased because of formation of the secondary phase Sm 2 Ti 2 O 7 . The dielectric constant decreased with increased Sm 3+ substitution. The effects of Sm 3+ substitution on dielectric loss and dielectric constant of the specimens were analyzed by the infrared reflectivity spectra in the range 50–4000 cm −1 , which were evaluated using the Kramers‐Kronig analysis and classical oscillator model. The correlations among dielectric constant, dielectric loss, and dispersion parameters were studied.