Ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer 70/30 thin films are prepared by spin coating. The crystalline structure of these films is investigated by varying the annealing temperature from the ferroelectric phase to the paraelectric phase. A hot plate was used to produce a direct and an efficient annealing effect on the thin film. The dielectric, ferroelectric and pyroelectric properties of the P(VDF-TrFE) thin films are measured as a function of different annealing temperatures (80 to 140 °C). It was found that an annealing temperature of 100 °C (slightly above the Curie temperature, Tc) has induced a highly crystalline β phase with a rod-like crystal structure, as examined by X-ray. Such a crystal structure yields a high remanent polarization, P_r = 94 mC/m², and pyroelectric constant, p = 24 μC/m²K. A higher annealing temperature exhibits an elongated needle-like crystal domain, resulting in a decrease in the crystalline structure and the functional electrical properties. This study revealed that highly crystalline P(VDF-TrFE) thin films could be induced at 100 °C by annealing the thin film with a simple and cheap method.

Lead-free 0.88(Na_0.5Bi_0.5) TiO₃–0.084(K_0.5Bi_0.5) TiO₃–0.063BaTiO₃ (BNT–BKT–BT) piezoelectric ceramic powders were incorporated into a polyvinylidene fluoride-trifluoroethylene [P(VDF-TrFE)] copolymer matrix to form 0–3 composites. Composites with BNT–BKT–BT volume fraction Ø ranging from 0.10 to 0.40 were fabricated using a hot-press method. These compositions were poled using various procedures to produce three types of samples: one with only the ceramic phase poled; one with polymer and ceramic phases poled in the same direction; and one with the polymer and ceramic phases poled in opposite directions. The effect of the polarisation state on the piezoelectric coefficient d₃₃ and pyroelectric coefficient p of the composite was investigated as a function of the ceramic volume fraction Ø. For the purpose of steadying and compensating the polarization domain, extra free charges were added by the presence of BNT–BKT–BT. In the sample with both ceramic and polymer phases poled in the same direction, the pyroelectric coefficient increased from 26 to 95 μC m⁻² K⁻¹ when the ceramic volume fraction increased from 0–0.20; this is greater than that of the P(VDF-TrFE)-PZT 0–3 composites. In the sample with the phases of the composite film polarised in opposite directions, their piezoelectric activities were reinforced, and d₃₃ was found to increase from 28 to 40 (pC N⁻¹) with a change in ceramic volume fraction ranging between 0 and 30%. One promising usage of the enhanced pyroelectric composites with the ceramic phase and the copolymer phase poled in the same direction is that of sensing components within pyroelectric sensors, while integration in ultrasonic transducer applications is possible in the case of the enhanced piezoelectric composites with the ceramic phase and the copolymer phase poled in opposite directions.

This work shows the enhancement of the visible photocatalytic activity of TiO₂ NPs film using the localized surface plasmonic resonance of Au nanostructures.