Mechanism of thermal decomposition of yttrium nitrate hexahydrate, Y(NO3)3•6H2O and modeling of intermediate oxynitrates

The thermal decomposition of yttrium nitrate hexahydrate Y(NO3)(3)center dot 6H(2)O is a complex condensation process generating a tetramer arrangement Y4O4(NO3)(4) formed by alternating yttrium and oxygen atoms. The anions NO3 (-) attach themselves to the yttrium atoms. The tetramer gradually loses N2O5 and, through the formation of Y4O5(NO3)(2), is transformed into yttrium oxide. The bond lengths and bond angles of intermediate oxynitrates calculated using the molecular mechanics method rendered data compatible with the results of X-ray diffraction for related compounds.