The Characterization of Some Iron Chromates

As the first step in a systematic review of a range of iron(III) chromates, the Mossbauer chemical shifts, quadrupole splittings and linewidths have been measured for a number of compounds. These parameters have been correlated with available structural information and the correlations have been applied to compounds with unknown structures and to the thermal decomposition products of the double chromates MFe (CrO4)2.nH2O with M = Na, K, Rb , Cs, NH4. Decomposition of the ammonium salt follows a different pathway, with the new mixed-valence compound, FeCr2O6, as an apparent intermediate.