Lithium Ferrite: Synthesis, Structural Characterization and Electromagnetic Properties

Abstract

Abstract Lithium ferrite (LiFe5 O8 ) is a cubic ferrite, belongs to the group of soft ferrite materials with a square hysteresis loop, with high Curie temperature and magnetization. The spi- nel structure of LiFe5 O8 has two crystalline forms: ordered, β-LiFe5O8 (Fd3m space group) and disordered, α-LiFe5O8 (P41 32/P43 32 space group). It has numerous technological applications in microwave devices, computer memory chip, magnetic recording, radio frequency coil fabrication, transformer cores, rod antennas, magnetic liquids among oth- ers. It is also a promising candidate for cathode in rechargeable lithium batteries. In this work, the dc electrical conductivity, the impedance spectroscopy and the magnetization of Li2 O-Fe2 O3 powders, with [Li]/[Fe]=1/5 (mol), heat-treated at several temperatures, are studied and related to their structure and morphology. The structural data were obtained by X-ray diffraction and Raman spectroscopy, and the morphology by scanning elec- tron microscopy. The impedance spectroscopy was analysed in function of temperature and frequency, and it was observed that the dielectric properties are highly dependent on the microstructure of the samples. The dc magnetic susceptibility was recorded with a vibrating sample magnetometer, under zero field cooled and field cooled sequences, between 5-300 K. Typical hysteresis curves were obtained and the saturation magnetiza- tion increases with increase in heat-treatment temperature. Keywords: