Mn- and Fe-spinels' formation through sintering of pure and waste materials: Mechanical, electrical and magnetic properties

Abstract

This study focuses on fabrication of some spinel composites from pure and waste materials for electronic and magnetic applications. Six batches were designed from pure MgO, ZnO, Fe2O3, MnO2 and iron oxide extracted from alum sludge. The designed batches were sintered at 1250 and 1350 °C then investigated for their phase composition, microstructure, physical, mechanical, electrical and magnetic properties. The results indicated that, after sintering at 1350 °C, all batches formed spinel structures as main phases. The formed spinel structures were MgFe2O4, MgMn2O4, ZnMn2O4 and ZnFe2O4, in addition to some minor pervoskite structures. The batch that prepared from pure manganese and zinc oxides (B4), formed ZnMn2O4 spinel and exhibited the best densification parameters (bulk density; 4.7 g/cm3 and apparent porosity; 10%) as well as highest hardness (4.53 GPa). On the other hand, the specimen that fabricated from pure MgO, MnO2 and Fe2O3 (B2) formed MgFe2O4 and MgMn2O4 spinel structures and exhibited the highest electrical resistivity (1.3E + 09 Ohm.cm) as well as highest saturation magnetization (Ms = 24.948 emu/g).