Characterization and magnetic investigations of germanium-doped lithium ferrite

Structural and some magnetic properties of Ge-substituted lithium ferrites having the general formula Li0.5+0.5xGexFe2.5−1.5xO4 (where x=0.0, 0.1, 0.2, 0.3 and 0.4) prepared by the standard ceramic technique have been studied. X-ray diffraction analysis indicates that all compositions are formed in a single phase cubic spinel structure. The lattice parameter was determined for each composition and it was found to decrease with Ge content. The grain size ‘D’ was estimated from the scanning electron microscope micrographs and it was found that it increases with increasing Ge4+ ion substitution. The B–H loops were measured at room temperature at constant magnetic field (1550 A m−1) and constant frequency (50 Hz). Both theoretical and experimental magnetic moments are found to decrease with germanium concentration. This decrease in magnetic moment with germanium is attributed to Neél׳s two sublattices model according to which the magnetic moment is the vector sum of lattice magnetic moment. The initial permeability (µi) was measured as a function of temperature from room temperature up to 893 K. The Curie temperature TC was determined and has been found to decrease with increasing Ge content.