Impact of humidity on surface acoustic wave propagation in vanadium pentoxide xerogel-lithium niobate structure

The impact of ambient humidity on surface acoustic wave (SAW) propagation in the structure consisting of vanadium pentoxide xerogel (V2O5nH2O) layer deposited on a piezoelectric lithium niobate (LiNbO3) substrate has been studied. Thin V2O5nH2O layers were synthesized using sol–gel method and employed as humidity sensing materials. Freshly prepared layer drastically reduced the transmitted SAW signal, which later increased with time reaching saturation after more than 120 h at the level well below the free-surface value. The experimental observations of SAW behaviour were discussed and found related to the variations in resistance and dielectric permittivity of the V2O5nH2O.