부산대학교 도서관

The charge transfer salt (DT-TTF)4[Au(pds)2]3 (DT-TTF, Δ2,2′-bithieno[3,4-d]-1,3-dithiol; pds, pyrazine-2,3-diselenate) was prepared and characterised by X-ray diffraction, electrical conductivity, thermoelectric power, magnetic susceptibility and EPR measurements. This compound crystallises in the triclinic system, space group P1¯, with the unit cell parameters a=9.712(5) A˚, b=13.620(5) A˚, c=17.169(5) A˚, α=97.254(5)°, β=106.132(5)°, γ=95.956(5)°, V=2141.10(15) A˚3, Z=1. Its crystal structure consists of a bidimensional network of DT-TTF tetramers and orthogonal anions. The electrical properties indicate it is a small gap semiconductor (2Δ=190 meV), with a room temperature conductivity of σRT=2 S cm−1. The electrical and magnetic properties reveal two types of transitions occurring upon cooling. The first, at 238 K, as a second order change to a large gap semiconducting state and, a lower transition, of first order type, with a large hysteresis between 210 and 150 K, probably associated with a larger structural change in the DT-TTF network. [Copyright &y& Elsevier]