Changes in Crystal Phase and Electric Resistance of Mn-Co-Ni Oxide in Refiring Process

Abstract

Changes in crystal phase and electric resistivity of Mn-Co-Ni oxide were investi g ated in the temperature range of 600 to 1000 °. The starting material was prepared by firing th e Mn-Co-Ni oxide with a composition of 3.0: 1.9: 1.1 at 1400 °. Refiring between 600 a nd 1000° was carried out in an atmosphere of prepurified nitrogen. As a result, it was fou nd that the electric resistivity depended on the type of crystal phases, and the tetragonal s pinel of high temperature form had much higher electric resistivity than that of the cubic spinel.