ELASTIC PROPERTIES OF THIN-FILM PALLADIUM FOR SURFACE-ACOUSTIC-WAVE (SAW) SENSORS

The elastic constants and density of supported palladium film have bee n determined, together with their changes produced by exposure to a ga s concentration of 1% H-2 in N-2 at room temperature and atmospheric p ressure. The results have been obtained by comparing the experimental group and phase velocities of surface acoustic waves (SAWs) propagatin g along different substrates covered with the Pd film under test, with the theoretical values calculated using the perturbative approach. Me asurements of the phase velocity have been made on the films both befo re and after exposure to H-2. The data obtained have been compared wit h those relative to polycrystalline and single-crystal palladium and p alladium hydride (PdH0.66).