Structural analysis of molten K₂SO₄

The structure of molten K₂SO₄ has been investigated using the radial distribution function together with the correlation method based on X-ray scattering intensity data collected at ≈ 1150°C. The SO₄ tetrahedron which exists in the crystalline state of K ₂SO₄ is shown to be preserved in the molten state. The most likely model for the short-range arrangement is that of four near-neighbour potassium atoms situated around the SO₄ tetrahedron. One of the four potassium atoms practically occupies the corner-site and the others occupy the edge-sites. The nearest-neighbour K-O and K-S distance are r = 2.80 and 3.38 Å, respectively. The most likely model for the long-range arrangement is about thirteen K₂SO₄ units situated around one K ₂SO₄ unit with an average inter-unit distance of 7.0 Å.