Measurements of the double piezoelectric effect

For a piezoelectric device with multiple electrodes, it should be possible to quantitatively and conveniently measure the piezoelectric coefficient d( 31) by use of the double piezoelectric effect, without the need for any unu sual apparatus or a calibration sample. One pair of electrodes is used to e xcite the piezo, and another is used to measure the response. For example, for a piezoelectric tube this should allow measurement of d(31) as a functi on of temperature or of lateral offset voltage. An important correction to the current theory is described. Measurements on two piezo tubes are presen ted for excitation voltages in the range of 0.5-110 V-pp. An inductive prox imity sensor was used to measure the actual piezo motion. It is shown that the current theory disagrees with this and previous experiments by a simple factor of 2 for symmetric excitations. However, for asymmetric excitations the disagreement with theory is more complex, and the current theory does not accurately predict the effects of varying tube geometry. (C) 2000 Ameri can Institute of Physics. [S0034-6748(00)02704-0].