Single-phase cubic spinel structure MgCr2-xO4 compounds with a controlled Mg/Cr ratio were obtained in stoichiometric composition and Mg excessive region. All of those single phase samples were p-type semiconductor and their electrical resistivity decreased with increasing the Cr vacancy concentration. This result supports our former conclusion that electrical conduction mechanism of this system is based on the p-type semiconductor conduction due to electrical hole by Cr4+.
