Properties of the Anisimkin Jr.´ Modes in Quartz Plates

Dispersion curves, surface displacements, and displacement profiles over the plate thickness are numerically calculated for acoustic plate modes, propagating in fused and Y-rotated, X-cut quartz samples with thickness h/lambda in the range 0-4.5 (h, thickness; lambda, wavelength). The Anisimkin Jr.´ modes with velocity v_n close to that of longitudinal bulk wave v_L and the dominant longitudinal displacement u₁ distributed uniformly through the plate thickness are found in quartz crystals with cut angles mu = 120deg- 140deg and plate thickness h/lambda = 0-0.36, 0.94-1.78, 2.32- 3.08, and 3.64-4.44. The same modes in fused quartz are not found, except in a narrow region near zero thickness.