Pressure Raman Studies on Alkali-perrehenates (AReO sub 4) and TIReO sub 4 and Pressure-induced Phase Transitions

The perrehenates KReO sub 4, RbReO sub 4, CsReO sub 4 and TIReO sub 4 which crystallize in tetragonal scheelite or orthorhombic psuedoscheelite structure have been investigated by high pressure Raman Spectroscopy to 25 GPa in a diamond anvil cell. The Raman spectra reveal three pressure-induced phase transitions in KReO sub 4, RbReO sub 4 and TIReO sub 4 and two transitions in CsReO sub 4.