Hole-pinned defect-dipoles induced colossal permittivity in Bi doped SrTiO3 ceramics with Sr deficiency

Abstract Bi doped SrTiO3 ceramics with Sr deficiency, i.e. Sr1-1.5xBixTiO3 (x=0, 0.01, 0.05, 0.1), were prepared via conventional solid-state reaction route. A colossal permittivity (CP) over 104 with low dielectric loss less than 0.05 was obtained in x=0.05 Sr1-1.5xBixTiO3 ceramics. In addition, the dielectric constant is maintained at a value greater than 104 in the range of 102-105 Hz and almost frequency independent. Phase structure analysis and density functional theory calculations suggest that the Bi Sr ∙ - V Sr " - Bi Sr ∙ defect complex with hole-pinned defect-dipoles maybe responsible for the high-performance CP properties. This work gives a new way to achieve high performance CP materials in ABO3 perovskite ceramics.