Abstract
The relation between the change of lattice spacing of the (021) planes of Rochelle salt as a function of the change in voltage applied along the a-axis of the crystal has been determined by x-ray methods over the temperature range from approximately 10°C to 30°C. Measurements with a microscope of the strain set up in the crystal, due to a change in voltage applied along the a-axis, indicate that there is a one to one correspondence between the change of lattice constant as measured by x-rays and as determined from the measurements of strain. The piezoelectric modulus, d14, as determined by the inverse piezoelectric effect is larger than the values determined from the piezoelectric effect.