A Moreac et al 1996 J. Phys.: Condens. Matter 8 3569 doi:10.1088/0953-8984/8/20/005
A Moreac, A Girard and Y Delugeard
Show affiliationsA low- and high-frequency Raman scattering study of the neutral-to-ionic phase transition of TTF-CA as it relates to the temperature and hydrostatic pressure is reported. Around the transition, the variations of the intensities of several antisymmetric modes permit the determination of the phase diagram and therefore the confirmation of previous results. Under pressure, the more continuous character of the transition is confirmed unambiguously. On the other hand, an evolution under pressure of the mechanism of the transition is clearly shown. The soft mode is still observed at 4 kbar but with a softening which is less critical. Moreover, in the high-temperature phase, the broadening of several totally symmetric modes favours an order - disorder mechanism. So, our study performed under pressure clearly shows that the mechanism of the transition moves from a displacive mechanism to an order - disorder one.
Issue 20 (13 May 1996)
Received 29 January 1996
A Moreac et al 1996 J. Phys.: Condens. Matter 8 3569
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