Electric conduction of MgCr2O4 with spinel type crystal structure

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 w ere p-type semiconductors. The lattice constants increased with increasing the holding time in sintering. The electrical resistivity and the Seebeck c oefficient decreased with increasing holding time. These phenomena indicate an increase in the electron carrier density. The activation energies of co nduction and Seebeck coefficients differed by 0.3 eV. This suggests that th e conduction mechanism of this system is based not on band-type conduction, but on heat-activated p-type semiconductor conduction by electron holes in troduced by Cr vacancies.