Electric conduction of MgCr2O4 with spinel type crystal structure

Abstract

The Stoichiometric compound MgCr2O4 was sintered at various holding times from 10 min to 100 h. All samples had a single-phase spinel structure and were p-type semiconductors. The lattice constants increased with increasing the holding time in sintering. The electrical resistivity and the Seebeck coefficient decreased with increasing holding time. These phenomena indicate an increase in the electron carrier density. The activation energies of conduction and Seebeck coefficients differed by 0.3 eV. This suggests that the conduction mechanism of this system is based not on band-type conduction, but on heat-activated p-type semiconductor conduction by electron holes introduced by Cr vacancies.