Fluoride Composite Films Research Articles

Ferroelectric phase stability studies in potassium nitrate: Polyvinylidene fluoride composite films

The structural and thermal properties of potassium nitrate (KNO3): polyvinylidene fluoride composite films have been studied. Differential scanning calorimetry has been employed to characterize the phase transitions in the composite and x-ray diffraction has been used to quantify the crystalline phases. The ferroelectric phase (III) of KNO3 is stabilized relative to the paraelectric phase (II) at room temperature at concentration ⩽50wt%, with the largest proportion at 50wt%. The enthalpies and transition temperature width are also affected in the composite. The polarization hysteresis loops also show that the remanent polarization is largest at 50wt% of KNO3. The capacitance–voltage characteristics exhibit strong hysteresis with pronounced peaks and some asymmetry. The switching current behavior of the composite film was also investigated and supports the presence of ferroelectric phase in the composite film at room temperature.

Photoelectret and electrophotographic properties of barium titanate-polyvinylidene fluoride composite film

Photoferroelectric barium titanate (BaTiO3)-polyvinylidene fluoride (PVDF) composite films in the ratio 70∶30 are found to possess good photosensitivity in the visible region of the spectrum. Results on investigations of charge generation, trapping, recombination, discharge and retention properties of the composite film are presented in this paper. Photoinduced polarization is obtained in a BaTiO3-PVDF composite film by the simultaneous application of a d.c. field and illumination from an argon-ion laser or by white light. The dark (photo) polarization and the dark (photo) depolarization current decay characteristics of the polarized films have been studied under different experimental conditions. The studies show that the composite film retains good polarization for a fairly long time in the dark condition, and the magnitude of the depolarization current is comparable with that of BaTiO3 single crystal. Under illumination, the decay is fast enough to make use of the film for electro-photographic applications.

Photoelectret and electrophotographic properties of barium titanate-polyvinylidene fluoride composite film

Photoelectret and electrophotographic properties of barium titanate-polyvinylidene fluoride composite film