Structural analysis of molten Na2WO4

The structure of molten Na2WO4 has been investigated by the radial distribution function based on X-ray scattered intensity data collected at ≈ 760°C and has been analysed by the correlation method. WO4 tetrahedra existing in the crystalline state are shown to be preserved in the molten state. Various arrangements of sodium atoms around the WO4 tetrahedron are examined by the correlation method. The arrangement which gives the best agreement with the observed intensity curve of molten Na2WO4 is a model in which W—Na = 3.63 A and the sodium atom is situated in an intermediate position between one point contact and two point contact. The packing of Na2WO4 molecules in the molten state cannot be described by the single packing model, but requires a distribution of packing models, mainly b.c.c.