SUPERPOSITION MODEL ANALYSIS OF CR3-SULFATE DIHYDRATE( IN SODIUM AMMONIUM)

This paper discusses the application of the superposition model of New man to studies of local distortions around Cr3+ ions doped into sodium ammonium sulphate dihydrate. It is shown that local distortions and a model for the charge compensation mechanism can be derived from the s tandard use of the superposition model for two of the sites observed ( beta and beta'). The calculations were carried out for the spin Hamilt onian parameters measured at temperatures both above and below the pha se transition detected at 95 +/- 0.5 K. It is shown that the phase tra nsition induces a substantial decrease in the metal-ligand distance in CrO6 octahedra.