Down to the quantum limit at the neutral-to-ionic phase transition of (BEDT-TTF)-(ClMe-TCNQ): symmetry analysis and phase diagram.
We report on the neutral-to-ionic (N-I) phase transition in the one-dimensional organic complex (BEDT-TTF)-(ClMeTCNQ). The X-ray studies at room temperature show that the neutral phase of (BEDT-TTF)-(ClMeTCNQ) is already characterized by a polar long-range ordering, at variance with other charge-transfer compounds comprising noncentrosymmetric molecules. From a detailed neutron diffraction study of this complex under high pressure, we present the phase diagram of the N-I transition down to the quantum limit. We discuss the symmetry breaking associated with the transition and the evolution of its first-order character under pressure.
Lemée-Cailleau
M H
MH
Institut Max von Laue - Paul Langevin, BP 156, 38042 Grenoble Cedex 9, France. lemee@ill.fr
Collet
E
E
Buron-Le Cointe
M
M
Grach
N
N
Ouladdiaf
B
B
Moussa
F
F
Hasegawa
T
T
Takahashi
Y
Y
Roisnel
T
T
Cailleau
H
H
D007477:Ions; D008968:Molecular Conformation; D033363:Neutron Diffraction; D009570:Nitriles / Q000737:chemistry*; D044367:Phase Transition; D011312:Pressure; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D014961:X-Ray Diffraction
C472948:BEDT-TTF; D007477:Ions; D009570:Nitriles; D013438:Sulfhydryl Compounds; C013703:tetracyanoquinodimethane