Structure, thermal stability and electrical properties of zinc manganites

Zinc manganites ZnxMn3−xO4 were prepared by the thermal decomposition in air of oxalate precursors. The structure and the thermal stability of the oxides were determined and correlated with their electrical properties (resistivity, resistivity drift). The substitution of manganese by zinc in the spinel structure has a stabilizing effect against oxidation and phase transformation. The strong energetic Zn2+–O bonding slows down the cationic migration in the lattice. The zinc manganites are suited to high temperature NTC thermistors. The resistivity range is large and no ageing phenomenon is observed in the ceramics.