Microstructural characterization of MgFe₂O₄ powders

The electrical properties of MgFe₂O₄ spinel are such that it is suitable as a sensing element for humidity measurement devices. One of the most important targets to be reached for this kind of application is the possibility of designing the microstructure of spinel powder compacts, because of its strong relationship with the spinel humidity-sensitive electrical properties. Thermal decomposition of precipitated precursors allows one to achieve this target. This paper deals with the microstructural characterization of MgFe₂O₄ spinel powder samples, obtained by thermal decomposition of various hydroxide precursors, in comparison with that of MgFe₂O₄ samples prepared by solid state reaction of the corresponding oxides. The results demonstrate that the hydroxide precipitation process is effective in varying the morphology and the microstructure of the final MgFe₂O₄ powders with respect to that obtained by solid state reaction.