DEVIATION FROM STOICHIOMETRY OF MN-DOPED FERROUS OXIDE

The nonstoichiometry of the mangano-wustite solid solution (Fe1-xMnx)1-yO with x=0.037, 0.122 and 0.295 was measured as a function of temperature (1173-1473 K) and oxygen pressure at thermodynamic equilibrium in the whole range of its stability phase field. It has been shown that the deviation from nonstoichiometry of Mn-doped ferrous oxide increases as the oxygen pressure increases. At constant oxygen pressure the nonstoichiometry decreases with increasing temperature and with increasing manganese content the nonstoichiometry decreases. The dependence of y versus PO2 is described by the equation: log y=1/n log PO2 + A better than by the equation: log PO2 = M(O/Me)+N. The results for low Mn-content (x = 0.037 and 0.122) described by two straight lines, which indicates that in mangano-wustite, it is possible to postulate two ranges of y measurements with different properties. For high Mn-content only one range was observed. © 1990.