Controllable synthesis, XPS investigation and magnetic property of multiferroic BiMn2O5 system: The role of neodyme doping

In this work, a novel series of multiferroic materials BiMn2O5 doped by Neodyme has been prepared by a sol-gel method at low temperature. The crystallographic studies using X-ray diffraction and Rietveld Refinement techniques showed the formation of single-phase samples for all compositions, crystallizing in a mullite-type orthorhombic perovskite structure, space group Pbam (Z=4). The SEM techniques confirmed the formation of single-phase materials with excellent mapping distribution. Raman and infrared spectroscopic measurements were performed and combined with lattice dynamics simulations to describe the room-temperature vibrational properties of all samples. The X-ray Photoelectron Spectroscopy (XPS) were measured in the energy range of 0–1400 eV at room temperature. The Fermi level EF was defined with the accuracy of 0.127, 0.32 and 0.48 eV for BiMn2O5, Bi0.9Nd0.1Mn2O5 and Bi0.8Nd0.2Mn2O5 respectively. The X-ray photoelectron spectroscopy shows the existence of Mn4+ state. Magnetic measurements indicate Neél temperature TN at 31, 40 and 61 K for BiMn2O5, Bi0.9Nd0.1Mn2O5 and Bi0.8Nd0.2Mn2O5 respectively