Structural, spectral, rietveld refinement and cation distribution of nanoferrite NiFe2O4 doped with Mn

The spinel ferrite Ni1–xMnxFe2O4 system (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) have been successfully synthesized by using the flash auto-combustion method at 600 °C for 2 h. The annealed powders were characterized by X-ray diffraction (XRD), IR spectroscopy, transmission electron microscopy and scanning electron microscopy. The structural analysis confirms the formation of spinel phase with the presence of small ratio of a secondary phases. It was noticed from the XRD data that the increasing of Mn2+ content increases the lattice parameter from 8.345 to 8.421 Å and the size of crystallite decreases from 33.63 to 27.30 nm. The theoretical density ρx and the area of crystallite surface were calculated. IR study reveals the presence of tetrahedral and octahedral absorption bands ν1andν2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\nu_{1} \;{\text{and}}\;\nu_{2} { }$$\end{document} with two weak bands ν1′andν2′\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \nu_{1}^{\prime } \;{\text{and}}\;\nu_{2}^{\prime }$$\end{document}. The morphological observations show the formation of agglomerated grains with different shapes and sizes.