Pressure-induced amorphization of Na2Al2Si3O10•2H2O and KAlSi2O6 zeolites

Pressure-induced amorphization has been observed in two zeolites, natrolite Na(2)Al(2)Si(3)O(10)center dot 2H(2)O and leucite KAlSi2O6. Using Raman microprobe, amorphized samples were analysed in situ at high pressures at compression in methanolethanol medium in diamond anvil cell and also after release of pressure. Before amorphization, one crystal-to-crystal phase transition was observed in each zeolite. It was shown for Na(2)Al(2)Si(3)O(10)center dot 2H(2)O that the transition from crystalline to amorphous phase is partially reversible for compression to the peak pressure in the range of similar to 7-10 GPa and practically irreversible above similar to 10 GPa. Surprising, the dehydrated crystal KAlsi(2)O(6) exhibited very high quasi-stability, at compression up to 16 GPa for one day. Long time compression (For 15 days) led to almost full amorphization of KAlSi2O6.