The results are reported of the pressure (P) dependence of the electrical resistance (R), the thermoelectric power (Seebeck effect) (S), and compressibility as well as the time dependence of R at fixed P up to 20 GPa for four metallo-organics based on the BEDT-TTF (bisethylenedithiolo- tetrathiorulvalene) group, θ-(BEDT-TTF)2CsZn(SCN)4, α-(BEDT-TTF)2I3, β′-(BEDT-TTF) 2PF6, and (BEDT-TTF)-TCNQ. X-ray powder and single-crystal diffraction studies were also made on θ-(BEDT-TTF)2CsZn(SCN) 4 at high pressures up to P ∼ 10 GPa. The R values of all the crystals decreased with pressure up to P ∼ 3-5 GPa (low-pressure regime), and then the sign of dR/dP inverted (high-pressure regime). From the investigation of the mechanical and structural properties, these materials were found to have a large compressibility in the low-pressure regime, and a small one in the high-pressure region. In θ-(BEDT-TTF)2CsZn(SCN) 4 we observed pressure- induced reversible degradation (amorphization) in structure without a solid-phase reaction.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics