Influence of Elastic Coefficient C14 and Piezoelectric Coefficient E22 on the Surface Wave in Trigonal Piezoelectric Half Space

The propagation behavior of surface acoustic wave (SAW) on the free surface of trigonal crystals in half space is investigated in this study. On the basis of elastodynamics and piezoelectric theory, field governing equations are established and solved analytically. The phase velocity, electro-mechanical coupling factor, and wave structure are discussed. Results show that the surface wave, which has three displacement components, can propagate in the half space made of trigonal crystals. Phase velocity is a constant, which means that its surface wave is non-dispersed. Phase velocity and electro-mechanical coupling increase with the increase in elastic coefficient C
14
. This finding implies that phase velocity should be underestimated if elastic coefficient C
14
is omitted. The attenuation tendency of the surface waves is also discussed based on the wave structures. The results obtained provide theoretical guidance for non-destructive evaluation and design of SAW devices based on trigonal piezoelectric materials.