Structural and magnetic properties of pure and Mn-doped bismuth ferrite powders

Multiferroic materials are of great interest from the scientific and technological viewpoints based on their multifunctional behavior involving ferroelectricity, ferromagnetism, ferroelasticity and strong electromagnetic coupling properties. Among these materials, BiFeO3 (BFO), is a well-known multiferroic with simultaneous ferroelectricity (TC=1103K) and G-type antiferromagnetism (TN=643K). In this work, we doped BiFeO3 with Mn species and studied the doping effect on the corresponding magnetic properties, expected from the substitution of Bi³⁺ by Mn²⁺. Additionally, the optimum processing conditions to minimize the formation of any impurity phase were also identified. X-Ray Diffraction (XRD) characterization confirmed the formation of powdered impurity-free BFO in pure and 7 at.% Mn-BFO only after annealing of the precursor compounds at suitable temperatures and time (700°C, 15 minutes). Scanning Electron Microscopy (SEM) analyses were used to determine the size and morphology of synthetized powders. Vibrating sample magnetometry (VSM) measurements showed that maximum magnetization values increased with doping and reached a maximum value in the 7 at.% Mn-doped BFO annealed at 700°C for 15min; the corresponding magnetization in the non-saturated MH loops reached 0.68 emu/g. This behavior can be attributed to the actual incorporation of Mn species into the BFO lattice and the substitution of non-magnetic Bi species.