Piezoelectric properties of cadmium sulfide crystals

The binary compounds crystallizing in the cubic sphalerite or hexagonal wurtzite structures are the simplest piezoelectric crystals and hence of theoretical as well as potential practical interest. So far quantitative data were available only on natural crystals of zinc sulfide in the cubic form, but new methods of crystal growth provide single crystals of hexagonal cadmium sulfide up to 1 inch minimum dimension; adequate resistivity is assured by copper-doping and by exclusion of light during measurement. Piezoelectric and elastic constants were obtained by conventional measurements of resonance and antiresonance of fundamental modes, including contour modes of square plates, and capacitance measurement above and below resonance. The piezoelectric strain constant and coupling factor for the "parallel" mode are about 3 times the corresponding constants for quartz and cubic zinc sulfide. Dielectric constants are about 10.