Colossal permittivity in Ta-doped SrTiO3 ceramics induced by interface effects and defect structure: An experimental and theoretical study.

The lack of systematic research on the phase structure, defect structure, and polarization mechanism hinders the full comprehension of the colossal permittivity (CP) behavior for SrTiO 3 -based ceramics. For this purpose, Ta-doped SrTiO 3 -based ceramics were synthesized in an N 2 atmosphere with a traditional method. When the appropriate amount of Ta was doped, colossal permittivity (ԑ r ∼ 62505), low dielectric loss (tanδ ∼ 0.07), as well as excellent temperature stability (−70 °C–180 °C, ΔC/C 25°C ≤ ±15%) were obtained in the Sr 0.996 Ta 0.004 TiO 3 ceramic. The relationship between Ta doping, polarization mechanism, and dielectric performance was systematically researched according to experimental analysis and theoretical calculations. The first-principle calculations indicate that the Ta5+ ion prefers to replace the Sr-site. The defect dipoles and oxygen vacancies formed by heterogeneous-ion doping play an active role in regulating the dielectric performance of ceramics. In addition, the interface barrier layer capacitance (IBLC) effect associated with semi-conductive grains and insulating grain boundaries is the primary origin of colossal permittivity for Sr 1-x Ta x TiO 3 ceramics. The polarization mechanism and defect structure proposed in the study can be extended to the research of SrTiO 3 CP ceramics. The results have a good development prospect in colossal permittivity (CP) materials. [ABSTRACT FROM AUTHOR]