Tuning Ferroelectric, Dielectric, and Magnetic Properties of BiFeO3 Ceramics by Ca and Pb Co‐Doping

Abstract

Effects of Ca/Pb co‐doping on structure, ferroelectric, dielectric, and magnetic properties of BiFeO3 ceramics are investigated. A structure transition from a rhombohedral phase (space group R3c) to a cubic phase (space group Pmm) with the increment of Ca/Pb concentration is revealed by X‐ray diffraction and Raman spectra. In order to compensate the valence change caused by Ca2+ dopant, Pb ions present tetravalent state under the existence of Ca ions. The room‐temperature ferroelectric behavior depends upon Ca/Pb co‐doping and the structural transition in BiFeO3 ceramics. Meanwhile, the variation of the dielectric loss tangent in the frequency range of 102–107 Hz and the leakage current at room temperature illustrate that Ca/Pb co‐doping increases resistivity and reduces leakage current. Compared with that of Sr/Pb co‐doping, the co‐doping of Ca/Pb has improved the leakage current by two orders of magnitude, besides further increasing the ferroelectric polarization and dielectric properties under the same co‐doping concentration. In addition, enhanced ferromagnetism is observed with the increase of Ca/Pb content, which can be attributed to the effective suppression of spiral cycloidal spin structure and spin canting resulting from the structural transition.