US Patent 7521844 Piezoelectric single-crystal device and method of manufacturing the same

To provide a piezoelectric single-crystal device which can stably attain an electromechanical coupling factor k31 of 60% or more in the lateral vibration mode and a method of manufacturing the same. Specifically, the piezoelectric single-crystal device has the polarization direction 3 in the [110] axis of a pseudocubic system and has the direction normal to an end face 10c of the piezoelectric device within the solid angle range of the [001] axis ±35° including the [001] axis approximately orthogonal to the polarization direction 3. The electromechanical coupling factor k31 in the direction orthogonal to the polarization direction 3, in the so-called lateral vibration mode, is 60% or more.