High" or/3-quartz is described by Sosman 1 as hexagonal trapezohedral orenantiomorphous hemihedral. He points out that crystals of this classification should exhibit piezoelectricity when subjected to shear stresses. This classification may also be described as hexagonal holoaxial. 2 /%quartz will be here shown to possess piezoelectric properties which are characteristic of hexagonal holoaxial crystals.
The piezoelectric ~ and elastic constants 4 are referred to a set of Cartesian axes in which the Z-axis coincides with the axis of hexagonal symmetry and the X-axis with an axis of digonal symmetry. Only rectangular crystal cuts with faces parallel to the c06rdinate planes are here considered. An X-face, for example, is one which is normal to the X-axis. When this face is a major surface, the plate is called an X-cut. The center of the rectangular parallelepiped is chosen as the origin so that the X, Y, and Z-faces are located respectively at x = 4-x',y = 4-y',andz = 4-z'.
If the components of strain and stress are expressed in the notation of Love, 5 the components Px, Py and Pz of polarization (:an be shown to be: