A method of determining acoustical physical constants for piezoelectric materials by line-focus-beam acoustic microscopy.

We developed a new method of determining acoustical physical constants (elastic constant, piezoelectric constant, dielectric constant, and density) of piezoelectric materials with high accuracy. This method acquires velocities of leaky surface acoustic waves (LSAWs) excited on the water-loaded specimen surface, measured by line-focus-beam (LFB) acoustic microscopy, and bulk velocities of longitudinal and shear waves, measured with plane-wave transducers replacing the LFB device in the same system, together with the dielectric constants and density measured independently, for a small number of specimens. For LiNbO3 and LiTaO3 crystals, we demonstrated that we could accurately determine the constants by choosing proper propagation directions of LSAWs and bulk waves for three principal X-, Y-, and Z-cut specimens and one rotated Y-cut specimen [(104) plate for LiNbO3 and (012) plate for LiTaOa]. The accuracy is nearly the same as that for the constants determined only from the bulk wave velocities.