V. Kapustianik et al., ELECTRON-PHONON INTERACTION AND PHASE-TRANSITIONS IN [C2H5NH3](2)CUCL4 CRYSTALS, Physica status solidi. b, Basic research, 207(1), 1998, pp. 95-101
Optical and spectral investigations confirmed the availability of phas
e transitions in [C2H5NH3](2)CuCl4 at T-1 = 364 K, T-2(h) = 356 K, T-3
= 232 K. It has been found that the empirical Urbach rule is fulfille
d in all phases. It is shown, that in the high-temperature phases skel
etal vibrations of the C-N-C group interact with phonons, whereas in t
he low-temperature phases internal vibrations of the metal-halogen com
plex occur. A ferroelastic domain structure was observed using the pol
arising microscope in the temperature region 232 to 364 K.