Effect of Eu, Mn co-doping on structural, optical and magnetic properties of BiFeO₃ nanoparticles

Multiferroic Bi_1−xEu_xFe_0.975Mn_0.025O₃ (x=0.025, 0.05, 0.075, 0.1) nanoparticles were prepared by sol-gel route. The impacts of Eu, Mn co-doping samples on the properties of structural, morphology, optical band gap, ferroelectric and ferromagnetic have been systematic investigated. X-ray diffraction and rietveld refinement data reveal that Eu, Mn co-substitution could trigger cubic phase transformation. From the SEM images, the grains of all the samples are asymmetrical and anomalous in shape and interestingly, the particle size of the samples decrease from 200 to 500 nm to ~100 nm after doping. And we can obtain the content of dopants in the samples by energy-dispersive X-ray spectroscopy (EDS) analysis. UV–vis absorption spectra demonstrate a gradually decreasing of the direct optical band gap from 2.40 eV to ~1.49 eV with doping Eu and Mn in BFO. X-ray photoelectron spectroscopy (XPS) analyses illuminate that Eu, Mn-doping results in the increase of Fe³⁺ ions content in the samples. The significantly increased the remanent magnetization (M_r) and coercive field (E_c) were caused by Eu and Mn co-doping.