Cr doping effects on the structural and magnetic properties of BiFeO3 nanoparticles synthesized hydrothermal method

• The morphology and ferromagnetism of BiFeO 3 nanoparticles can be affected by Cr doping. • There is a limit concentration when Cr dopes BiFeO 3 nanoparticles by the hydrothermal method . • The existence of oxides is observed only through the analysis of the local structure of doped Cr. • The abnormal magnetic performance in Cr doped BiFeO 3 nanoparticles is related to the appearance of oxides. Chromium-doped multiferroic bismuth ferrite BiFe 1-x Cr x O 3 (x = 0.0, 0.05, 0.10, 0.15, 0.20) nanoparticles were synthesized by the conventional hydrothermal method. The effects of Cr doping on the structural and magnetic properties of BiFeO 3 nanoparticles were investigated at room temperature using X-ray diffraction (XRD), X-ray absorption fine structure (XAFS) spectroscopy and superconducting quantum interference device (SQUID). From the scanning electron microscope (SEM) images, the morphology of BiFeO 3 nanoparticles was effected obviously by Cr doping, though the actual doping concentrations were below 4% according to the inductively coupled plasma mass spectrometry (ICP-MS) results. The XRD results showed that all samples had rhombohedral R 3 c crystal structure without any impurity phase, and further confirmed by the Bi L 3 -edge and Fe K -edge XAFS spectra. However, the Cr K -edge XAFS results of the doped samples revealed the presence of the oxides related Cr as the doping concentration increase. Furthermore, different Cr-doped concentrations played an important role on the magnetic enhancement of BiFeO 3 , and the abnormal performance of magnetism might be attributed to the unexpected oxides.