Acoustoelectric effects in reflection of leaky-wave-radiated bulk acoustic waves from piezoelectric crystal-conductive liquid interface

• Radiation of bulk acoustic waves by leaky surface acoustic wave.
• Acoustoelectric interaction at the piezoelectric crystal-conductive liquid interface.
• Characterization and identification of liquids using leaky surface acoustic waves.

The leaky surface acoustic wave (SAW) propagating along X-axis of Y-cut lithium tantalate crystal strongly radiates energy in the form of an obliquely propagating narrow bulk acoustic wave (BAW) beam. The reflection of this beam from the crystal–liquid interface has been investigated. The test liquids were solutions of potassium nitrate in distilled water and of lithium chloride in isopropyl alcohol with the conductivity varied by changing the solution concentration. The strong dependences of the reflected wave amplitude and phase on the liquid conductivity were observed and explained by the acoustoelectric interaction in the wave reflection region. The novel configuration of an acoustic sensor for liquid media featuring important advantages of separate measuring and sensing surfaces and rigid structure has been proposed. The application of leaky-SAW radiated bulk waves for identification of different brands of mineral water has been demonstrated.