Pressure-induced noble gas insertion into Linde-type A zeolite and its incompressible behaviors at high pressure

High-pressure behaviors of Linde-type A (LTA) zeolite were investigated using a quasi-hydrostatic pressure medium of noble gases (helium or argon). High-pressure in situ X-ray diffraction measurements combined with the use of a diamond anvil cell did not observe any structural phase transition for LTA zeolites up to a pressure of approximately 12 GPa at room temperature. However, it was found that the compressibility strongly depended not only on the pressure medium but also on the pressurization process. LTA zeolites showed significant incompressible behaviors at pressures between 2 and ∼7 GPa when it was compressed in helium. Based on careful analyses of the data together with the results of previous high-pressure studies, the incompressibility of LTA zeolites was induced by the penetration of a large amount of noble gas atoms into the cages of LTA zeolites under high pressures. The present results offer interesting and important information on the atomic diffusion process for open-structured materials under high pressures and thus have great implications for the development of new noble-gas-atom filled materials, as well as geochemical implications.