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Microwave Dielectric Properties and Thermally Stimulated Depolarization Currents of (1 − x )MgTiO 3 – x Ca 0.8 Sr 0.2 TiO 3 Ceramics
Author(s) -
Zhang Jie,
Yue Zhenxing,
Zhou Yuanyuan,
Zhang Xiaohua,
Li Longtu
Publication year - 2015
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.13485
Subject(s) - dielectric , analytical chemistry (journal) , materials science , dielectric loss , microwave , oxygen , phase (matter) , depolarization , ceramic , mineralogy , chemistry , metallurgy , optoelectronics , medicine , physics , organic chemistry , chromatography , quantum mechanics , endocrinology
(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 [ ( Ti Ti ′ ) − ( V O ∙ ∙ ) ] and in‐grain oxygen vacancies ( V O ∙ ∙ ) 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.