Highly improved multiferroic properties of Sm and Nb co-doped BiFeO3 ceramics prepared by spark plasma sintering combined with sol-gel powders

Multiferroic BiFeO 3 and Bi 1- x Sm x Fe 0.95 Nb 0.05 O 3 ceramics are successfully fabricated by spark plasma sintering combined with sol-gel powders. The effects of Sm and Nb co-doping on the structural, dielectric, ferroelectric and magnetic properties of the samples are investigated. With the Sm-Nb co-doping, the crystal structure of as-prepared samples transforms from R 3 c to Pnma and the grain size, loss tangent and leakage current density are reduced. The leakage current density of the co-doped samples can be reduced by approximately three orders of magnitude compared with the undoped sample. The dielectric, ferroelectric and magnetic properties are apparently enhanced due to the Sm-Nb co-doping. The optimal values of remanent polarization ( P r ) and magnetization ( M r ) of the created Bi 0.85 Sm 0.15 Fe 0.95 Nb 0.05 O 3 ceramic are approaching up to 5.853 μC/cm 2 and 0.187 emu/g, respectively. This enhancement of the multiferroic properties could be attributed to the co-doping-induced structural distortion, grain size reduction, oxygen vacancy decrease, space-modulated spin structure collapse as well as increased magnetic ions.