Study on the crystal structure refinement and magnetic properties of Al doped NdFeO₃ system

Al doped orthoferrites NdFe_1-xAl_xO₃ was synthesized by solid state reaction. X-ray powder diffraction and the rietveld refinement results show a decrease in the lattice parameters as Al doping content x increasing. Higher Al doping level leads to significant change on Fe-O bond length as well as Fe-O-Fe bond angle in the unit cell, and such change shows different behaviors in the directions of a, b and c axis. Magnetic properties of the sample are significantly affected by the structure change of the sample, which was caused by Al doping. Magnetic measurement results indicate that weak ferromagnetic ordering resulted from Dzyaloshinsky-Moriya (D-M) interaction was reduced with the increasing Al doping content and the phase transition temperature of spin reorientation interaction owing to the interaction between Nd ion and Fe ions moves to lower temperature with higher Al doping level. Furthermore, magnetization of the sample was decreased along with the increasing Al-doping content, indicating that the canted antiferromagnetic structure is evidently modulated by the nonmagnetic Al-doping in Fe site.