Aspect ratio dependence of d(15) measurements in Motorola 3203 material

The measurement of piezoelectric coefficients is a subject that has receive d considerable attention, with the exception of shear mode excitation. The aspect ratios necessary to provide accurate, reproducible measurements of d (15) in Motorola 3203 are explored using impedance spectroscopy. It is show n that a minimum aspect ratio of 20:1 is necessary in the dimensions of the ceramic between the field and the polarisation directions (l/t) to provide reproducible measurements, contrary to previous work. A width contribution to the measurement results is highlighted leading to a minimum aspect rati o of 6:1 between the width and the thickness (w/t). It is suggested that th e width contribution is a result of a distribution of dipole vectors around the poled direction. (C) 2000 Elsevier Science Ltd. All rights reserved.