Changes in Electron-Phonon Coupling Across a Bulk Phase Transition in Copolymer Films of Vinylidene Fluoride (70%) with Trifluoroethylene (30%)

Authors

C.N. Borca, University of Nebraska-Lincoln
Shireen Adenwalla, University of Nebraska-LincolnFollow
Jaewu Choi, Louisiana State University, Baton RougeFollow
Lee Robertson, Oak Ridge National Laboratory
H. You, Argonne National Laboratory; 9700 S. Cass Avenue, Argonne, IL
V.M. Fridkin, The R~tssiaizA cademy of Sciences, 59 Leninsky Prospekt, I17333 Moscow: Russia
S.P. Palto, The R~tssiaizA cademy of Sciences, 59 Leninsky Prospekt, I17333 Moscow: Russia
N. Petukhova, The R~tssiaizA cademy of Sciences, 59 Leninsky Prospekt, I17333 Moscow: Russia
Peter A. Dowben, University of Nebraska-LincolnFollow

Date of this Version

2001

Comments

Published in Applied Surface Science 175-176 (2001) 265-269. Copyright (c) 2001. Used by permission.

Abstract

We present evidence for a change in electron-phonon coupling across a bulk phase transition. Below the lattice stiffening transition at around 160 K, there is a change in the diffracted peak width observed by neutron and X-ray scattering techniques. Also, the electronic band structure of the copolymer is shifting in binding energy below 160 K, decreasing the density of states near the Fermi level. The value of the effective Debye temperature above the transition temperature is approximately 50 K, while below 160 K, the value of the Debye parameter is 245 K. We postulate that the coupling between electrons and phonons results in a static distortion of the lattice (below 160 K), and this distortion "melts" above 160 K.