Site-substitution in GdCrO 3: Effects of Mn valence states on structural, magnetic and electric properties

GdCr 1- x Mn x O 3 (0 <= x <= 0.3) was prepared by sol-gel method, the effect of Mn doping on the microstructure, magnetic and electric properties of GdCrO 3 were studied. The results indicate that all samples have a good orthogonal perovskite structure. The main diffraction peak and lattice parameter varied non -monotonically with the increase of Mn ions in XRD. This is related to the change in valence state of Mn ions, which has been confirmed by X-ray photoelectron spectroscopy (XPS). The positron annihilation lifetime spectrum indicates that vacancy defects and local electron density are related to the valence states of Mn ions. It can be noted from UVVis spectroscopic measurements that the doping of Mn ions leads to a decrease in the optical band gap ( E g ) from 3.11 eV to 2.13 eV for GdCrO 3 . The temperature dependence curve of the magnetization intensity curves show that T N (Cr) decreases with Mn ions. The nonmonotonic variations of magnetic moment and remanent magnetization strength are associated with the valence state of Mn ions and the magnetic interactions after doping, respectively. In addition, the samples have low dielectric constants at low doping and the reverse at high doping, which is also related to the valence state variation of Mn ions.