Effect of gas adsorption on the elastic properties of faujasite films measured using magnetoelastic sensors

A novel method is presented for measuring the elastic properties of zeolite films using magnetoelastic sensors. The method is relatively simple and can be used to determine the effect of adsorbed molecules on the mechanical properties of the zeolite film. It is demonstrated using NaX films grown on Metglas ribbons. Measurements were taken as a function of temperature (10-40 degrees C) and gas (CO2, N-2, vacuum) for a range of sensors with different faujasite masses (0.25-8.0 mg). For each temperature and gas, the modulus of elasticity of the faujasite crystalline film was extracted by analyzing the measurements as a function of film thickness. For all temperatures examined, it was found that the elastic modulus of the NaX films in vacuum was 38.7 +/- 1.7 GPa. On the other hand, in the presence of N2, it varied between similar to 24 and similar to 38 GPa and, when in contact with CO2, between similar to 39 and similar to 52 GPa. Our results show for first time that the adsorption of gases in zeolites might induce changes in the elastic properties of the zeolite crystals. Finally, even though this method was applied to a zeolite film, it is quite general, and it can be used for measuring the elastic modulus of any microporous or mesoporous film.