Dear colleguas,
While measuring D33 coefficient of an unpoled piezopolymer PHB (polyhydroxybutyrate) membrain, negative D33 coefficient is observed every time, no change of sign of coefficient occurs upon changing side of membranes.
Should the sign of d33 coefficient be changed when reversing an unpoled piezopolymer thin membrane? Is there any method to measure D33 of thin film deposited on metal substrate? Does the traditional ‘Berlincourt meter’ suit for measurement of thin films?
Thanks in advance for your answeres!