The influence of ZrO2 additive on sintering and microstructure of lithium and lithium-titanium-zinc ferrites

Abstract

The effect of ZrO2 addition (0–3 wt%) on sintering and microstructure of lithium and lithium-titanium-zinc ferrites was studied. The Vickers hardness and dc electrical resistivity were investigated and discussed in correlation with the structural properties. Ferrite powders with the chemical compositions of LiFe5O8 and Li0.65Fe1.6Ti0.5Zn0.2Mn0.05O4 were prepared by the conventional ceramic technique. The synthesized ferrites were doped with various amount of ZrO2 and then were sintered at 1050 °C for 2 h. Dilatometric studies showed that the zirconia addition affects the densification process of ferrite ceramics so that the shrinkage rate of pressed ferrite powders during their heating decreased with an increase in ZrO2 content. The bulk density of the sintered ferrites varied slightly as the concentration of the additive was increased from 0 to 2 wt%, while the density of ferrite doped with 3 wt% ZrO2 significantly decreased. X-ray diffraction and scanning electron microscopy analyses showed that the lattice parameter of ferrites increases and their average grain size decreases as the additive content grows. It was established that small amounts of ZrO2 additive (up to 2 wt%) improve significantly the hardness and the electrical resistivity of ferrites.