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

Multiferroic BiFeO3 and Bi1-xSmxFe0.95Nb0.05O3 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 R3c 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 Bi0.85Sm0.15-Fe0.95Nb0.05O3 ceramic are approaching up to 5.853 mu C/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. (C) 2019 Elsevier B.V. All rights reserved.