Some crystal to glass transitions at high pressures

The α-GeO2, α-AlPO4, Ni(OH)2 and LiCsSO4 are shown to undergo crystal to amorphous transitions under pressure. α-GeO2 and α-AlPO4, being isomorphous with α-quartz, were presumed to undergo crystal to crystal phase transition prior to amorphization similar to that seen in α-quartz. However, no such phase transition is observed in them. Ni(OH)2 which is isomorphous with Ca(OH)2 and Mg(OH)2, becomes x-ray amorphous at ∼ 13 GPa. LiCsSO4 undergoes a series of crystal to crystal phase transitions, in agreement with the earlier Raman scattering studies, and finally amorphizes at pressures greater than 15 GPa. (author)