Correlation of charge defects and morphology with magnetic and electrical properties of Sr and Ta codoped BiFeO3

Abstract The influence of co-substitution of Sr 2+ and Ta 5+ on the structural, morphological, electrical and magnetic properties of BiFeO 3 ceramics was investigated. The ceramic pellets of Bi 0.8 Sr 0.2 Fe 1−x Ta x O 3 (x = 0 to 0.15) were synthesized by adopting solid state reaction method. Rietveld refinement of X-ray diffraction data reflected that all ceramics had rhombohedral structure ( R 3 c ). A second phase was observed to appear for maximum amount of Ta 5+ (x = 0.15) doping. The effect of Sr 2+ and Ta 5+ doping on the grain size distribution was monitored and their corresponding relation with electrical and magnetic properties were elucidated. Theoretical bond strength was calculated with thermodynamic analysis for different phases to correlate with the experimental findings. Although the addition of Sr 2+ increased leakage current, Ta 5+ doping suppressed it by approximately 2 orders of magnitude. Dielectric property measurement also showed a decrease in dielectric constant at room temperature with an increase of Ta 5+ . Moreover, the addition of Ta 5+ up to 10 mol.% enhanced the magnetic property. The possible reasons for the reduction of leakage current and improvement of ferromagnetic property were also discussed in this contribution.