APPLICATION OF SYNCHROTRON-RADIATION TO T HE STUDY OF HIGH-PRESSURE ZEOLITE PHASES - CASE OF SCOLECITE

Pressure-induced amorphization has already been observed in some frame work silicates like quartz and feldspars. A similar crystal to highly disordered solid transition is reported in this study fora zeolite nam ed scolecite, which is the calcium end-member of the natrolite group. Pressure-induced amorphization is demonstrated using in-situ X-ray dif fraction and Raman spectroscopy. This transformation is preceded by po lymorphic transitions and occurs below 10 GPa. The crystal-amorphous t ransition is irreversible and the pressure quenched samples exhibit Ra man spectra which bear strong resemblance with alumino-silicate glasse s obtained by quenching a liquid. In some cases however, decompression is accompanied by a rim recrystallisation of the sample. The role of shear stresses seems thus to be crucial during the decompression of th e samples.