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

Borca, C. N. ; Adenwalla, S. ; Choi, J. ; Robertson, L. ; You, H.

Technical Information Center Oak Ridge Tennessee

关键词: Electron-phonon coupling;    Copolymers;    Transition temperature;    Lattice parameters;    X ray scattering;   

RP-ID  :  DE2001768608

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

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 shifling 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.