REDUCTION OF IMPURITY IONS IN MgO BY CURRENT FLOW 4T HIGH TEMPERATURE (*)

Results of a study of the reduction of transition metal impurity ions in MgO due to passage of electric current are reported. Fields of the order of 103 V/cm and temperatures between 950 and 1 150 °C were used. Trivalent impurities, Fe3+ and Cr3+ could be almost completely redu­ ced, whereas divalent Mn2+ was not greatly changed. V2+ appeared after treatment; presumably vanadium had been in the 3+ state in the original MgO. The results further indicate that the reduc­ tion process is not uniform throughout the samples, that it can be reversed by heating in the absence of an electric field, and that it is accompanied by the creation of defects that act as shallow electron trapping sites at room temperature.