Abrupt Slope Change in Temperature Dependence of Resistivity in Ni-Fe-O Sintered Body

Abstract

NiFe₂O₄+ 0∼100 vol.% NiO sintered bodies were prepared by mixing NiFe₂O₄ and NiO powders, and subsequent sintering at 800°C in air for 1 hour. Slopes in the temperature dependence of resistivity curves in the system have been found to abruptly changed, except for a composition of NiFe₂O₄+ 50 vol.% NiO. To investigate the mechanism of this phenomenon, NiFe₂O₄ powder was analyzed by high temperature X-ray diffraction, a thermo-gravimetry and differential thermo analysis. In the range from 100 to 300°C, the structure of NiFe₂O₄ phase does not change. Therefore the mechanism of this phenomenon is not related to any phase transition or the contamination of NiO.