High-pressure phase transitions in Li2SO4 center dot H2O

High-pressure Raman spectroscopic investigations are carried out on Li2SO4. H2O up to a pressure of 18.1 GPa. Changes in the Raman spectra suggest two structural transitions occurring around 2.6 and 7.0 GPa, respectively. Dis continuous changes in the internal mode frequencies of sulfate ions around 2.6 GPa indicate that the transition involves reorientation of SO4 ions. A comparison of the behavior of the high-pressure phase in this compound with those in other Li-based binary sulfates indicates that the orientational d isorder in these compounds at high pressures arises due to dissimilar catio ns. (C) 2000 Elsevier Science B.V. All rights reserved.