The effect of ageing due to annealing of corona charged PVF films has been studied by observations of (i) changes in the X-ray diffraction patterns and (ii) decay of the piezoelectric strain coefficient d. Annealing at progressively higher temperatures was observed to produce a gradual depolarization although considerable piezoelectricity was still remanent even at 150°C, The structural morphology of the corona charged PVF was not significantly altered by annealing at temperatures up to 150°C.
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