Verteilung und Valenz der Kationen in Spinellsystemen mit Eisen und Chrom, II. Zur Stöchiometrie des Spinells FeCr2O4 / Distribution and Valence of the Cations in Spinel Systems with Iron and Chromium, II. On the Stoichiometry of the Spinel FeCr2O4

FeCr2O4 has been prepared under CO-CO2-atmosphere with oxygen partial pressures between 10-18 and 10-8 bar. X-Ray and Mößbauer investigations show that under higher pressures FeCr2O4 is not stoichiometric but contains Fe(III), and that corund type Cr2O3 as an additional phase has been formed. In the wide pressure range from 10-17 to 10-14 bar the contents of Fe(III) are lower than 1% of total iron, and the corund phase is negligible.