Piezoelectric coupling factor calculations for plates of langatate driven in simple thickness modes by lateral-field-excitation

Piezoelectric coupling factors for langatate (La/sub 3/Ga/sub 5.5/Ta/sub 0.5/O/sub 14/) single-crystals driven by lateral-field-excitation have been calculated using the extended Christoffel-Bechmann method. Calculations were made using published materials constants. The results are presented in terms of the lateral piezoelectric coupling factor as functions of in-plane (azimuthal) rotation angle for the three simple thickness vibration modes of some nonrotated, singly-rotated, and doubly-rotated orientations. It is shown that lateral-field-excitation offers the potential to eliminate unwanted vibration modes and to achieve considerably greater piezoelectric coupling versus thickness-field-excitation for the rotated cuts considered and for a doubly-rotated cut that is of potential technological interest.