Vibrational spectroscopic study of the ferroelectric phase transition in vinylidene fluoride-trifluoroethylene copolymers: 1. Temperature dependence of the Raman spectra

Coupling Mechanical and Electrical Properties in Spin Crossover Polymer Composites

“…The Raman spectra of the composite were found homogenous and consist of the superposition of the spectra of 1 and P(VDFTrFE) (see Figure 1e; Figures S12-14 in the Supporting Information). At room temperature the well-known fingerprints of the LS phase of 1 (131, 207 and 288 cm −1 ) [32] and the so-called β phase of the P(VDF-TrFE) matrix (840 cm −1 ) [33] can be clearly discerned. When the temperature is increased above ≈340 K a decrease of the intensity of the LS markers is observed while other peaks, characteristic of the HS phase, emerge around 103, 144, and 190 cm −1 .…”

“…These values are reduced with respect to the −20 pC N −1 measured for the pure P(VDF-TrFE). Smaller values of d 33 are generally observed in composites with nonferroelectic loads. [37] This decrease of d 33 may be attributed to the action of depoling field generated by space charges on the particles during poling.…”

“…Poling of samples was undertaken at 293 K by applying several cycles of a sinusoidal electric field (100 mHz) with amplitudes up to 13.6 and 18 MV m −1 . The resulting piezoelectric coefficient d 33 , which provides direct information on the mechanical to electrical (and vice-versa) conversion efficiency, was −2.3 and −3.3 pC N −1 , respectively. These values are reduced with respect to the −20 pC N −1 measured for the pure P(VDF-TrFE).…”

Polarization fluctuation dominated electrical transport processes of polymer-based ferroelectric field effect transistors

“…[34][35] There have been reports where the FE transition of PVDF has been followed by Raman measurements. 36 The spectra of P3HT coated on PVDF-TrFE retained the features of the constituents, similar to P3HT on Si as a function of T. There was a change in the background of the Raman spectra in the PE-phase, which was reversible as the temperature was cycled to the FE-phase. However, the broadening and frequency shifts of the P3HT Raman peaks as a function of T were identical for P3HT on Si and PVDF-TrFe, indicating that the changes in the transport properties at the T c arises mainly from the coupling of charge carriers with the dielectric interface.…”

Voltage-induced Infrared Absorption from a Spin-cast Thin Film of Ferroelectric Poly(vinvlidene fhioride-co-trifluoroethvlene) (P(VDF-TrFE))

“…The ferroelectric properties are considered to originate from inversions of the polymer chains containing polar -CF2-groups at the molecular level. Molecular and solid-state structures of P(VDF-TrFE) films have been studied using X-ray diffraction, 31,32 Raman spectroscopy, 31,33 and infrared spectroscopy. 31,[34][35][36] P(VDF-TrFE) is used as a ferroelectric dielectric in the memory field-effect transistors because P(VDF-TrFE) ferroelectric thin films can be easily prepared by the spin-casting method.…”