Influence of Sintering on the Structural, Electrical, and Magnetic Properties of Li–Ni–Mn–Zn Ferrite Synthesized by Citrate Precursor Method

Substituted lithium ferrites having the compositional formula Li0.35−0.5x Nix Mn0.1 Zn0.2 Fe2.35−0.5x O4 where 0.1 ≤ x ≤ 0.3 in steps of 0.05 had been synthesized by the citrate precursor method. The samples were given single sintering at 900 °C and double sintering, second sintering at 900 °C after a pre-sintering or first sintering at 600 °C. Spinel phase structure was confirmed from FTIR spectra and XRD patterns. A study on the structural parameters (lattice constant, density, porosity and crystallize size), electrical parameters (dielectric constant ε′\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \varepsilon^{'} $$\end{document}, dielectric loss tangent tanδ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ tan\delta $$\end{document}, dc resistivity ρdc), and magnetic parameter (initial permeability μi′\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \mu_{i}^{'} $$\end{document}) of single-sintered (SS) and double-sintered (DS) Li–Ni–Mn–Zn ferrite samples has been investigated. Structural studies reveal that DS samples enhance density and reduce porosity. Electrical studies showed lower value of dielectric constant, and dielectric losses while higher dc resistivity is observed in DS samples. However, in both series, an anomalous high increase in dielectric constant for x = 0.15 is observed. It was found from magnetic studies that the initial permeability is lower in the DS samples. The mechanism that involves in the results obtain above is being discussed.