Pressure-Induced Neutral-Ionic Phase Transition in the Mixed-Stack 21 Charge-Transfer Complex (EDT-TTF-I-2)(2)TCNQF

Arkadiusz Frqckowiak (1) , Roman Swietlik (1) , Lucky Maulana (2) , Di Liu (2) , Martin Dressel (2) , Olivier Jeannin (3) , Marc Fourmigué (3)

1 PAN - Polish Academy of Sciences
2 Universität Stuttgart [Stuttgart]
3 ISCR - Institut des Sciences Chimiques de Rennes

We explored the neutral-ionic phase transition in (EDT-TTF-I-2)(2)TCNQF by measuring the electrical conductivity as a function of temperature and hydrostatic pressure (up to 11.8 kbar). At about 4.3 kbar, the compound undergoes the transition to a quasi-ionic phase at the temperature about 100 K; the transition temperature increases as the pressure grows. We propose a pressure-temperature phase diagram, discussed in comparison to analogous data obtained for mixed-stack 11 charge-transfer complexes, which also undergo a neutral-ionic transition. We suggest that the transition smearing can be related with the fact that, in this 21 complex, not only the Madelung energy but also the ionization potential of donors grows as the crystal lattice contracts upon decreasing temperature.

Domains: Chemical Sciences

Arkadiusz Frqckowiak, Roman Swietlik, Lucky Maulana, Di Liu, Martin Dressel, et al.. Pressure-Induced Neutral-Ionic Phase Transition in the Mixed-Stack 21 Charge-Transfer Complex (EDT-TTF-I-2)(2)TCNQF. Journal of Physical Chemistry C, 2020, 124 (10), pp.5552-5558. ⟨10.1021/acs.jpcc.9b11786⟩. ⟨hal-02562366⟩