Colossal permittivity and low dielectric loss in Ta doped strontium titanate ceramics by designing defect chemistry

The environmentally friendly and high effective colossal permittivity (CP, > 104) ceramic materials play an indispensable role in the development of electronic field. In this research, SrTi1-xTaxO3 (0.000 ≤ x ≤ 0.014) (STTO) ceramic samples were fabricated by sintering in nitrogen atmosphere. It can be found that the CP (22790@1 kHz, 22063@1 MHz), low dielectric loss (0.012@1 kHz, 0.025@1 MHz), good stability of frequency (20–106 Hz) and temperature (25–350 °C) were achieved simultaneously for x = 0.010 ceramic samples. Meanwhile, the mechanism of achieving CP and low dielectric loss was deeply discussed based on the sintering of different atmospheres and the analyses of SEM and XPS. Through experimental comparison, it can be detected that modest TiTi’−VO⋅⋅−TiTi’ defect dipoles and VO⋅⋅−3TiTi’−TaTi⋅ defect clusters were main reasons for CP and dielectric loss, which can hinder the long-range transition of electrons and bring about electrons movement within narrow areas. Consequently, the local polarization of electrons increased the permittivity and suppressed the long range motion of electrons, which resulted in low dielectric loss in a wide range of frequency.