Crystal structure analysis of the orthorhombic phase II of KLiSO4

The crystal structure of the orthorhombic high-temperature phase II (708-94 9 K) of KLiSO4 was analyzed by single-crystal neutron diffraction. The ambi guity concerning the symmetry of this phase is solved and a disordered stru cture is established in the space-group Pcmn. Hence, KLiSO4 II is confirmed to be isostructural to the highest-temperature modification I of RbLiSO4. The investigated KLiSO4 crystals were pseudohexagonally twinned with three ferroelastic domain states according to the phase transition from P6(3) (ph ase III at room temperature) to Pcmn (phase II). (C) 2000 Elsevier Science B.V. All rights reserved.