Microwave Dielectric Properties and Thermally Stimulated Depolarization Currents of (1 − x)MgTiO₃–xCa_0.8Sr_0.2TiO₃ Ceramics

Abstract

1 -x)MgTiO 3 -xCa 0.8 Sr 0.2 TiO 3 (0.04 ≤ x ≤ 0.2, MT-CST) composite ceramics were prepared by the conventional solidstate 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 s 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 ½ðTi 0 Ti Þ À ðV O Þ and in-grain oxygen vacancies ðV O Þ increased with the increasing x, which could induce microwave dielectric loss consequently. It demonstrated that the behaviors of Q 3 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 e r = 21.19, Q 3 f = 110 900 GHz (f = 9.295 GHz), and s f = -0.9 ppm/°C, respectively. P. Davies-contributing editorManuscript No. 35752.

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