抄録
Stability against chemical reduction is one of most important material property for high temperature thermistor materials. In this paper, material design of spinel type MgCr2O4 by first principles calculation in collaboration with experiments was discussed. MgCr2O4 is known to show Cr-deficit p-type semi-conduction in the elevated temperature region. The theoretical calculations of Cr-vacancy formation energy showed preferred formation of Cr-vacancies and their stability in oxidizing atmosphere, while their instability in reduction atmosphere. The stable semi-conducting Po2 region (i.e. 1 to 10-10 atm at 1000°C) of MgCr2O4 was determined by precise experiments. First principles calculation can be a powerful tool for the ceramic material design, when they are used in collaboration with precise experiments.
