L. Burianova et al., Piezoelectric hydrostatic coefficients of PVDF and P(VDF-TrFE) copolymer foils at high hydrostatic pressures, FERROELECTR, 224(1-4), 1999, pp. 457-466
Pressure dependence of the hydrostatic piezoelectric coefficient d(h) was m
easured for PVDF and P(VDF-TrFE) polymer foils in the range up to 60MPa. Th
e hydrostatic strain coefficient d(h), the hydrostatic voltage coefficient
g(h) and figure of merit d(h).g(h) were determined using the static method.
Electric charge induced across samples was measured by Keithley 6517 elect
rometer and the pressure in the measuring chamber was changed by using a ho
me made hydraulic press. The pressure dependences of hydrostatic coefficien
ts were measured for several cycles. A pressure hysteresis was observed the
re. Permittivity of the polymer foils was measured as a function of pressur
e using an HP 4192A Impedance Analyser. Experimental dependences of the cha
rge on pressure and temperature were fitted by multi parameter function. Th
e pressure and temperature dependences of the hydrostatic d(h) and pyroelec
tric p(3) coefficients were determinated. It was found the hydrostatic stra
in coefficient d(h) decreased and pyroelectric coefficient p(3) increased w
ith pressure at constant temperature.