In situ observation of the pressure-induced amorphization of siliceous faujasite.

Zeolites are formed from rigid tetrahedral aluminosilicate units corner-linked to form rings which are in turn fully corner-linked to form larger units, resulting in open structures with large pores and often cavities. When subjected to pressure, zeolites can undergo pressure-induced amorphization and the resulting amorphous form has a structure and physical properties that are different from amorphous forms (often glasses) produced more conventional routes. It is the aim of this experiment to evaluate the changes in zeolite structure (i.e., the progressive loss of long-range order) up and to the point of amorphization at pressures of 2.2 GPa. This in situ experiment will use a completely siliceous zeolite, which lacks aluminium and charge balancing cations and is also water-free. High pressure neutron diffraction data will be collected in two geometries, transverse detector banks will be used to collect data to high values of scattering vector, which will be used to monitor the progressive collapse of the zeolite while low Q data will be collected using longitudal banks to determine the topology and porosity retention in the high-pressure amorphous form.