“Fast” quasilongitudinal sagittally polarized surface waves in layer-substrate structures

Abstract

The propagation of surface sagittally polarized waves on the plated surface of a semi-infinite medium with the phase velocity exceeding that of bulk quasitransverse sagittally polarized waves in the substrate is studied analytically and numerically. Such a surface wave is shown to exist in nonpiezoelectric and piezoelectric composites provided both the sagittal plane and the interface are planes of elastic symmetry of the layer and substrate. In the case of a nonpiezoelectric structure, the "fast" surface wave is one-component, involving only the quasi-longitudinal nonuniform mode in the substrate. In piezoelectrics this wave is two-component and incorporates the quasilongitudinal mode and the mode of electrical potential in the substrate. The "fast" wave exists at definite values of the velocity nuF and the layer thickness/wavelength ratio (h/lambda)F. It has been found that one or two surface waves can arise for the same direction of propagation at different nuF and (h/lambda)F, in the case of two surface solutions, both the values of (h/lambda)F being small. The approximate expressions are derived which allow one to elucidate whether the structure under consideration can support the "fast" surface wave and to estimate the corresponding nuF and (h/lambda)F. A comparison is performed of numerical and analytical results.

Interface waves on the sliding contact between identical piezoelectric crystals of general anisotropy

“…[14], B 44 remains positive at the limiting velocity if LBW is not piezoactive. Hence, the second equation in (27) can have at most one root. On the other hand, the LBWs associated with TS4 are piezoactive and B 44 → −∞ as v →v 1 (Fig.…”

“…Such an approach has been successfully applied to surface and interface acoustic wave theory in non-piezoelectric and piezoelectric media [11][12][13][14][15][16][17][18][19][20][21][22]. The same method has allowed one to study the occurrence of quasi bulk waves on the corrugated surface of anisotropic substrates [23], to analyze properties of the frequency spectrum of acoustic waves propagating under metallic gratings [24] as well as the existence of leaky waves and high-velocity non-attenuating localized waves in homogeneous and layered structures [25][26][27][28].…”

On the theory of the elastic wave propagation in a crystal coated with a solid layer. II. Surface and leaky waves near a line of exceptional bulk waves

“…It has recently been found that for certain symmetric geometries of propagation pure surface waves appear on the plated surface of a solid in the rangev 2 < v <v 3 (Naumenko & Didenko 1999;Didenko et al 2000;Darinskii 2000b;Darinskii et al . 2000).…”

Non-leaky longitudinal acoustic modes in ScxAl1-xN/sapphire structure for high-temperature sensor applications

“…They have specific one-partial structures and are located on the leaky SAW branch arising from the longitudinal BAW propagating in the substrate. The existence conditions for HVSAWs, with requirements to combined substrate and film materials, were derived analytically in [12].…”