Alteration of magnetic behavior and microstructural distortion of EuMnO3 by partial substitution of Eu with monovalent Na

Abstract

Effect of monovalent sodium doping on inherent lattice distortion and magnetic properties of EuMnO3 is reported in this work. Perovskite structured Eu1-xNaxMnO3 (x = 0.0, 0.1, 0.2) compounds are prepared by conventional sol-gel method. Inherent structural distortion of EuMnO3 and its modification by Na doping is investigated by analyzing powder X-ray diffraction patterns of these compounds. Numerical values of different structural and microstructural parameters related to structural distortion are evaluated by Rietveld analysis of XRD patterns. Different distortions in MnO6 octahedra are shown by 3D atomic models. The value of Goldschimdt tolerance factor is calculated as 0.8711 for the undoped compound and 0.8870 and 0.8856 for the 10mol% and 20mol% Na doped compounds respectively. Na doping stabilizes the orthorhombic perovskite structure and reduces both octahedral and Jahn-Teller distortion by increasing the average R site ionic radii and by introducing non Jahn-Teller Mn+4 ions in the compound. Magnetic behaviors of the compounds are studied by temperature dependent magnetization measurement. Anti-ferromagnetic EuMnO3 with Neel temperature 33 K transforms to ferromagnetic Eu1-xNaxMnO3 with Curie temperature 42.5 K and 42.9 K for10 and 20mol% Na doping respectively. However, 10mol% Na doping found to be more effective than 20mol% for stabilization of structure and reduction of octahedral distortion as well as in introducing ferromagnetic ordering.