Microwave Dielectric Properties and Thermally Stimulated Depolarization Currents of (1 −  x )MgTiO ₃ – x Ca 0.8 Sr 0.2 TiO ₃ Ceramics

(1 − x )MgTiO 3 – x Ca 0.8 Sr 0.2 TiO 3 (0.04 ≤ x ≤ 0.2, MT ‐ CST ) composite ceramics were prepared by the conventional solid‐state reaction process. The phase composition, microwave dielectric properties, and microwave dielectric loss mechanisms were studied. Ca 0.8 Sr 0.2 TiO 3 was employed as a τ f compensator for MgTiO 3 , and they coexisted well without forming any secondary phases. Interestingly, significant dielectric relaxations associated with oxygen vacancy defects were observed in all the MT ‐ CST ceramics through the dielectric‐temperature spectra. Thermally simulated depolarization current was therefore conducted to obtain the defects associated with extrinsic dielectric loss mechanisms. The concentrations of both defect dipole and in‐grain oxygen vacancies increased with the increasing x , which could induce microwave dielectric loss consequently. It demonstrated that the behaviors of Q × f were basically influenced by phase composition and defects here. Temperature‐stable ceramics can be achieved at x = 0.06, where the microwave dielectric properties were ε r = 21.19, Q × f = 110 900 GHz ( f = 9.295 GHz), and τ f = −0.9 ppm/°C, respectively.