Reactions of liquid sodium with transition-metal oxides. Part VIII. The oxides of chromium-(III),-(IV), and -(VI) and disodium chromium(VI) tetraoxide

The reactions of the chromium oxides CrO3, CrO2, Cr2O3, and Na2CrO4 with liquid sodium have been studied at up to 600 °C, in some cases using differential thermal analysis. The reaction products have been examined by powder X-ray crystallography. The ternary oxide NaCrO2 is formed in each case in which reaction took place, and this compound does not react further with dissolved oxygen in sodium up to the solubility limit. It is shown that the reaction of CrO3 with liquid sodium does not yield Na2CrO3 as previously thought; this error is rationalised in terms of the experimental procedure, and improved techniques are identified.