High-temperature structure analysis of KLiSO 4 by neutron powder diffraction

Abstract

The high-temperature structures of potassium lithium sulfate, KLiSO 4, were refined by neutron powder diffraction and the Rietveld method. In addition to the room temperature structure of KLiSO 4, which is referred to as Phase III, two different high-temperature structures are referred to phase II (708–943 K) and Phase I (943–989 K). The crystal structures of phase II at 753 and 793 K were refined on the basis of both the centrosymmetrical (space group Pmcn) and the non-centrosymmetrical (space group P2 1cn) models. The crystal structure of phase I at 963 K was also refined on the basis of these two models with the space group P6 3mc and P6 3/mmc. The refined structures at high temperatures were compared with each other and the positional disorders of the oxygen atoms in the structures of phase II and I were discussed.