Abstract
The suitability of square plates, vibrating in contour modes, for the determination of piezoelectric coefficients is considered. Piezoelectric measurements on such plates provide checks for the theoretical solution of the various modes and in particular for the distribution of displacement. The recently published solutions for square plates form a basis for this work and the reliability of these solutions is discussed. The materials used were sodium chlorate, sodium bromate, quartz, ammonium dihydrogen phosphate and ethylene diamine tartrate (EDT). New determinations of the elastic and piezoelectric coefficients of these materials have been made, with the exception of EDT, the data for which were published in a previous paper