| Anisimkin Jr.’ modes discovered recently in quartz plates [1] are found now in two other piezoelectric crystals, belonging to trigonal symmetry. In 1280Y,X+900-LiNbO3 two different QL modes may propagate simultaneously for small plate thickness h/λ = 0 - 0.06 (h – thickness, λ - wavelength). Velocity of the 1st mode v1 is close to the longitudinal bulk wave velocity vL. It is varied with h/λ and piezoelectrically stiffened (maximum Kn2 = 39/% at h/λ = 0.08). Velocity of the 2nd mode v2 is close to the shear-horizontal bulk wave velocity vQSH, not varied with h/λ and not stiffened (Kn2 = 0). On the contrary, 2100Y,X-Te crystal supports only one QL-mode, but it is unusually wide-ranging and low-dispersive: the mode exists for all h/λ from 0 to 2.5 with velocity vn almost permanent and equal to vL in the whole range. This mode is piezoelectrically stiffened. Its coupling constant approaches 2/% at h/λ = 0.13. Variety of the Anisimkin Jr.’ modes in different crystals makes them attractive for liquid sensors, where suitable waves have been restricted till now by SH counterparts. |