Acoustoelectric investigation of V2O5·nH2O thin film transition from wet gel to xerogel

• Application of surface acoustic waves for monitoring gel-to-xerogel transition
• Strong acoustoelectric interaction in LiNbO3–V2O5·nH2O structure
• Contactless measurement of V2O5·nH2O film conductivity
• Extraction of water content n in V2O5·nH2O

The strong acoustoelectric interaction in thin films of vanadium pentoxide hydrate (V2O5·nH2O) fabricated by the sol–gel method on the YZ LiNbO3 substrate was investigated using the surface acoustic wave (SAW) technique. Significant variations of the SAW amplitude and phase during a few first hours after the structure fabrication were attributed to the changes in the film conductivity linked to the water loss in the V2O5·nH2O films during the transition process from wet gel to xerogel. The SAW measurements revealed that the conductivity of vanadium pentoxide hydrate films linearly increased with time as the water amount, n, in V2O5·nH2O decreased according to a logarithmic law from 8 to 6.3. The estimated interlayer distance between V–O layers in the hydrate structure was 23 Å–21 Å.