Effect of high energy milling on the synthesis temperature, magnetic and electrical properties of barium hexagonal ferrite

Nanoparticles of barium hexagonal ferrite (BaFe12O19) have been synthesized by initial high energy milling of the precursors and sintering subsequently. X-ray Diffraction pattern reveals the hexagonal phase with a crystallite size of 42 nm. Scanning Electron Micrograph (SEM) shows the size of nanoparticles to lie in the range of single domain particles. X-ray Photoelectron Spectroscopy (XPS) indicates Fe in +3 state and an associated surface peak indicates its presence at different environments. Vibrating Sample Magnetometer measurements (VSM) illustrate ferrimagnetism with high coercivity and non-saturation of hysteresis behavior up to 8500 Oe. The initial high energy milling confines the particle size to the nanoscale which leads to high coercivity. Temperature dependent magnetization shows a sharp peak before transition which is the characteristic of the single domain magnetic behavior. Resistivity plot shows a decreasing trend with temperature. Two thermal activation energy values of 0.81 eV and 0.29 eV indicate the existence of two different conduction processes. The frequency dependent dielectric constant plot shows a semiconducting behavior. The dielectric loss plot shows a drastic change at high temperature due to the anion vacancies in addition to four types of polarization. (C) 2014 Elsevier B.V. All rights reserved.