Neutron scattering study of the phases of TTF-TCNQ below 5 kbar

Recent transport data by Friend et al. and elastic neutron scattering data from Megtert et al. have shown a variety of interesting changes in the low-temperature properties of tetrathiaful-valene-tetracyanoquinodimethane (TTF-TCNQ) when under high pressure. As a further elucidation of this problem, we have used elastic neutron scattering to make a more detailed study of the pressure-temperature phase diagram up to pressures of 4.75 kbar. We report the pressure dependence of the structural transitions which occur at 49 and 38 K at $P=1\mathrm{}$ bar. In addition, we describe a new low-temperature phase found for $3.25<P<\mathrm{}4.0\mathrm{}$ kbar.