A. V. Bune

Piezoelectric and pyroelectric properties of ferroelectric Langmuir-Blodgett polymer films

The piezoelectric and pyroelectric responses of ferroelectric Langmuir–Blodgett polymer films are less than the largest values measured with bulk films of the same composition. The films of the crystalline copolymer poly(vinylidene fluoride trifluoroethylene) fabricated by the Langmuir–Blodgett technique are 30 ML thick (15 nm) and are highly crystalline and oriented with polarization perpendicular to the film. Both piezoelectric and pyroelectric measurements show reversible ferroelectric switching. The films are suitable for use in pyroelectric infrared imaging and in piezoelectric acoustic transducers.

Novel switching phenomena in ferroelectric Langmuir-Blodgett films

We have established ferroelectric switching and observed a novel conductance switching phenomenon in ferroelectric polymer films fabricated by the Langmuir–Blodgett technique. The films consist of 10–30 monolayers (ML) of a copolymer of vinylidene fluoride (70%) and trifluoroethylene (30%), exhibiting a first‐order ferroelectric phase transition at 70 °C and nearly rectangular ferroelectric and conductance hysteresis at 24 °C. Ferroelectric switching is accompanied by switching of the conductance by three orders of magnitude. A model describing this switching phenomenon is proposed.

Ultrathin ferroelectric polymer films

Abstract We have established ferroelectric switching and observed a novel conductance switching phenomenon in the first ultrathin ferroelectric polymer films fabricated by the Langmuir-Blodgett technique. The films consist of up to thirty monolayers of a copolymer of vinylidene fluoride (70%) and trifluoroethylene (30%) and exhibit classic ferroelectric behavior, including a first-order ferroelectric phase transition, polarization reversal (switching), thermal hysteresis of the capacitance, field-dependent switching dynamics, pyroelectricity, and piezoelectricity. The results of polarization, capacitance, switching, spectroscopic, and pyroelectric measurements on these highly crystalline and fully oriented films provide unprecedented detail concerning the thermodynamic properties of the ferroelectric and nonferroelectric states in ultrathin polymer films. The electric field and the film thickness have a strong influence on the ferroelectric properties.

Optical sensitization at the phase transition in the ferroelectric vinylidene fluoride‐trifluoroethylene copolymer

At the ferroelectric phase transition in the optically sensitized ferroelectric vinylidene fluoride‐trifluoroethylene copolymers P(VDF‐TrFE) the sharp change of the dye energy level is revealed. In ferroelectric P(VDF‐TrFE) copolymer doped by indolynospiropyran the structural chromic effect is observed, which is characterized by the reversible change of the film color at the ferroelectric phase transition.

EoC21a. Photoconducting ferroelectric polymers

Abstract The new photoconducting ferroelectric polymer is prepared by means of dye sensitization of ferroelectric vinylidene fluoride-trifluoroethylene copolymers P(VDP-TrFE). The photoconductivity, the bulk photovoltaic effect and photochromic effect have been observed in the spectral bands connected with dye molecules absorption. The new photoconducting ferroelectric polymer may be used as the photorefractive material. By means of the photochromic effect in the ferroelectric copolymer doped by indolynospiropyran the transmission gratings were received. At the ferroelectric phase transition the sharp changes of the dye energy level and oscillator strength are revealed.

Ferroelectricity at molecular level

The synthesis of ultrathin ferroelectric nanostructures by the Langmuir–Blodgett method and their properties are reviewed. It is shown that ferroelectricity exists in one monolayer of the ferroelectric P(VDF-TrFE) copolymer, i.e., at the molecular level. The specific characteristics of switching of ultrathin ferroelectric films are established.

Absorption changes at the phase transition of ferroelectric copolymers doped by a cyanine dye

Abstract At the ferroelectric phase transition in the optically sensitized ferroelectric vinylidene fluoride-trifluorethylene copolymers P(VDF-TrFE) the sharp change of the dye energy level and optical absorption is revealed. In ferroelectric P(VDF-TrFE) copolymer doped by cyanine due to the structural chromic effect is observed, which characterized by the reversible change of the film color at the ferroelectric phase transition.

Photochromic gratings in the optically sensitized ferroelectric copolyher

Abstract The ferroelectric vinylidene fluoride-tri-fluorethylene copolymer P(VDF-TrFE) was doped by rhodamine 6G and indolynospiropyran. In the optically sensitized ferroelectric copolymer the photoconductivity, oulk photovoltaic and photochromic effects were observed. By means of the photochromic effect in the ferroelectric copolymer doped by indolynospiropyran the transmission gratings were received. The obtained photochromic gratings may be used for the light deflectors and holographic optical storage.

Photoelectric properties of the ferroelectric polymer PVDF

Abstract The photoconductivity, the bulk photovoltaic effect (BPE) and the photoelectret effect have been observed experimentally in polymer ferroelectric films of polyvinylidene fluoride (PVDF). The reciprocal influence of the photoelectret internal field on the hysteresis loop and the ferroelectric switching on the photoelectret charge are reported.

Some investigations of photoelectric and optic properties in the ferroelectric PVDF

Abstract The photoconductivity and the bulk photovoltaic effect(BPE) have been observed experimentally in the polymer ferroelectric films of polyvinylidene fluoride (PVDF) under the illumination in the visible range. The effect of polarization of light by the thick samples of PVDF has been investigated.