Surface Electrical Properties of the Wustite Phase

Abstract

The iron‐oxygen system has been studied using work function measurements between 675° and 950°C, the stability range of the wustite phase. The work function of wustite vs. nonstoichiometry indicates a decrease of the Fermi energy below 850°C while for the temperatures between 900° and 950°C an initial decrease is followed by the final increase. The measured work function data depend only on the temperature and oxygen partial pressure. This indicates that the system is well equilibrated. The values of the partial pressures of oxygen corresponding to the wustite phase equilibria with iron and with magnetite determined in this work agree well with the reported literature data. A short equilibration time favors the work function method as a convenient one for investigating phase diagrams of oxide systems. The experimental data do not confirm the p‐ to n‐type transition postulated for on the basis of earlier measurements of the Seebeck coefficient.