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Title: The effect of interlayer interactions on the ferroelectric-paraelectric phase transition in multilayered thin films of vinylidene fluoride-trifluoroethylene copolymers.

Abstract

The interaction between ferroelectric polymer films with different transition temperatures is evident in the effect of layer thickness on the ferroelectric-paraelectric phase transition in multilayer films, as revealed by x-ray diffraction and dielectric measurements. The multilayer samples consisted of alternating Langmuir-Blodgett (LB) films of two different copolymers of vinylidene fluoride with trifluoroethylene, one with 80% vinylidene fluoride and a ferroelectric-paraelectric transition temperature on heating of 133 {+-} 4 C and the other with 50% vinylidene fluoride and a transition temperature of 70 {+-} 4 C. Samples with a repeat period of 20 LB layers (10 contiguous layers of each composition) exhibited two distinct phase transitions, indicative of minimal interaction between the two materials. Films with a repeat period of 2, or films made from an equal mixture of the two copolymers, exhibited composite behavior, with an intermediate transition temperature and suppression of the transitions associated with the individual compositions. Films with a repeat period of 10 exhibit cross-over behavior. These results imply that the ferroelectric interaction length along the (110) direction, which is perpendicular to the film plane, is approximately 11 nm.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
914919
Report Number(s):
ANL/MSD/JA-58386
TRN: US200817%%161
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Phys. Cond. Matter; Journal Volume: 19; Journal Issue: 2007
Country of Publication:
United States
Language:
ENGLISH
Subject:
36 MATERIALS SCIENCE; COPOLYMERS; DIELECTRIC MATERIALS; FLUORIDES; HEATING; MIXTURES; POLYMERS; THICKNESS; THIN FILMS; TRANSITION TEMPERATURE; X-RAY DIFFRACTION

Citation Formats

Kim, J., You, H., Ducharme, S., Adenwalla, S., Materials Science Division, and Univ. of Nebraska. The effect of interlayer interactions on the ferroelectric-paraelectric phase transition in multilayered thin films of vinylidene fluoride-trifluoroethylene copolymers.. United States: N. p., 2007. Web. doi:10.1088/0953-8984/19/8/086206.
Kim, J., You, H., Ducharme, S., Adenwalla, S., Materials Science Division, & Univ. of Nebraska. The effect of interlayer interactions on the ferroelectric-paraelectric phase transition in multilayered thin films of vinylidene fluoride-trifluoroethylene copolymers.. United States. doi:10.1088/0953-8984/19/8/086206.
Kim, J., You, H., Ducharme, S., Adenwalla, S., Materials Science Division, and Univ. of Nebraska. Mon . "The effect of interlayer interactions on the ferroelectric-paraelectric phase transition in multilayered thin films of vinylidene fluoride-trifluoroethylene copolymers.". United States. doi:10.1088/0953-8984/19/8/086206.
@article{osti_914919,
title = {The effect of interlayer interactions on the ferroelectric-paraelectric phase transition in multilayered thin films of vinylidene fluoride-trifluoroethylene copolymers.},
author = {Kim, J. and You, H. and Ducharme, S. and Adenwalla, S. and Materials Science Division and Univ. of Nebraska},
abstractNote = {The interaction between ferroelectric polymer films with different transition temperatures is evident in the effect of layer thickness on the ferroelectric-paraelectric phase transition in multilayer films, as revealed by x-ray diffraction and dielectric measurements. The multilayer samples consisted of alternating Langmuir-Blodgett (LB) films of two different copolymers of vinylidene fluoride with trifluoroethylene, one with 80% vinylidene fluoride and a ferroelectric-paraelectric transition temperature on heating of 133 {+-} 4 C and the other with 50% vinylidene fluoride and a transition temperature of 70 {+-} 4 C. Samples with a repeat period of 20 LB layers (10 contiguous layers of each composition) exhibited two distinct phase transitions, indicative of minimal interaction between the two materials. Films with a repeat period of 2, or films made from an equal mixture of the two copolymers, exhibited composite behavior, with an intermediate transition temperature and suppression of the transitions associated with the individual compositions. Films with a repeat period of 10 exhibit cross-over behavior. These results imply that the ferroelectric interaction length along the (110) direction, which is perpendicular to the film plane, is approximately 11 nm.},
doi = {10.1088/0953-8984/19/8/086206},
journal = {J. Phys. Cond. Matter},
number = 2007,
volume = 19,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • Polymer nanocomposite was prepared using poly(vinylidene fluoride-trifluoroethylene) and zinc oxide (ZnO) nanopowder, which are ferroelectric in nature. Nanocomposite was prepared in various concentrations(0.2, 0.4, 0.8, and 1 wt. %) using probe ultra-sonication, followed by spin coating and annealing at 120 °C for 2 h to improve the formation of β-phase. Metal-ferroelectric-metal capacitor was fabricated using this optimized thin film as a ferroelectric layer. Device level optimization was carried out by polarization-electric field (P-E) hysteresis studies of this film, which shows polarization enhancement of composite. Various characterization techniques like atomic force microscopy, Fourier transform infra-red spectroscopy (FT-IR), Differential scanning calorimetry, and X-ray diffractionmore » were used to study the β-phase formation of nancomposite. The capacitance–voltage (C-V) and current-voltage (I-V) characteristics were studied through varying frequency and temperature. C-V measurements show an increase of 79% in the capacitance of polymer nanocomposite, which can be used for the fabrication of ferroelectric devices.« less
  • We observed a clear polarization reversal-induced resistance switching effect in ferroelectric Vinylidene-fluoride (VDF)/Trifluoroethylene (TrFE) copolymer thin films. Pt and Au were used as the bottom and top electrodes, respectively, and the thickness of the VDF/TrFE copolymer film was adjusted to be 10 nm. The conduction current was 100 times higher in the case of the spontaneous polarization of the VDF/TrFE film towards the Au electrode than that in the case of the opposite direction. This resistance switching was confirmed to be reproducible after 10 successive polarization reversals.
  • Surface structures and a surface structure phase transition are identified that are distinct from the known bulk ferroelectric-paraelectric phase transition of crystalline copolymer films of vinylidene fluoride (70%) with trifluoroethylene (30%). The temperature-dependent changes in the surface structure are accompanied by the physical rotation of the polar group (CH{sub 2}-CF{sub 2}). These changes in the surface structure are compared to the bulk phase transition. We show that the bulk structural transition, while distinct from the surface, is qualitatively similar in both thick and thin Langmuir-Blodgett-grown films. (c) 2000 The American Physical Society.
  • The β phase stability in poly(vinylidene fluoride/trifluoroethylene) [P(VDF-TrFE)] thin films was studied below 300 K using X-ray diffraction and polarization-electric-field (P-E) hysteresis loops measurements. On as-grown samples, an irreversible partial order-disorder transformation at T{sub β} ∼ 250 K, namely, the β relaxation temperature, was evidenced by the appearance of an additional X-Ray diffraction peak above T{sub β} as well as changes on the P-E loops on heating after the first cooling. This order-disorder-like transformation which is attributed to an all-trans order to helical disorder transition is suggested to take place in defect-rich regions like crystal-amorphous interphases and/or crystalline areas with randomly distributed TrFE defect-likemore » units.« less
  • Oxygen plasma etching characteristics of ferroelectric poly(vinylidene fluoride-trifluoroethylene) copolymer films are investigated. It was found in MFM (M: metal; F: ferroelectric) capacitors that plasma damage effects to the ferroelectric properties were insignificant when Au metal masks were used. On the contrary, C-V (capacitance versus voltage) characteristics were significantly degraded in plasma-etched MFIS (I: insulator; S: semiconductor) diodes. The origin of this phenomenon is speculated to be degradation of the SiO{sub 2}/Si interface by energetic oxygen ions and then mixing of Kr gas to the oxygen plasma is attempted to decrease the plasma damage.