We report the discovery of a compressibility phase transition at 160 K in crystalline copolymer films of vinylidene fluoride (70%) with trifluoroethylene (30%). This phase transition is distinct from the known bulk ferroelectric-paraelectric phase transition at 353 K and surface ferroelectric phase transition at 295 K. The new phase transition is characterized by an increase in the effective Debye temperature from 48 to 245 K along the 〈010〉 direction as the temperature falls below 160 K. This phase transition is evident in neutron scattering, x-ray diffraction, angle-resolved photoemission, and in the dipole active phonon modes in electron energy-loss spectroscopy. © 1999 The American Physical Society.
Publication Source (Journal or Book title)
Physical Review Letters
Borca, C., Adenwalla, S., Choi, J., Sprunger, P., Ducharme, S., Robertson, L., Palto, S., Liu, J., Poulsen, M., Fridkin, V., You, H., & Dowben, P. (1999). Lattice-stiffening transition in copolymer films of vinylidene fluoride (70%) with trifluoroethylene (30%). Physical Review Letters, 83 (22), 4562-4565. https://doi.org/10.1103/PhysRevLett.83.4562