Toshiaki TANAKA,* Tooru ATAKE,* Zurong SHI, Chikako NAKANO, Toshiaki ENOKI,* Gunzi SAITO** and Hiroo INOKUCHI (*Tokyo Inst. Tech., **Kyoto Univ.)
[J. Phys. Chem. Solids 58, 295 (1997)]
The heat capacity of tetrakis(alkylthio)tetra-thiafulvalenes (TTCn-TTF, n=3,8) was measured by adiabatic calorimetry between 10 and 330 K. TTC3-TTF and TTC8-TTF had melting points at 306.58 and 322.51 K with enthalpy of fusion of 42.7 and 89.3 kJ mol-1, respectively. The liquid phase of TTC3-TTF could be cooled down to liquid helium temperature without crystallization, and a glass transition was observed at about 205 K. In the heating run, the supercooled liquid transformed into a metastable solid phase at about 225 K, and then it transformed into the stable solid phase at about 270 K. In the case of TTC8-TTF (Form II), two solid-solid phase transitions of the first-order type were found at 94.3 and 215.8 K with enthalpy of transition of 0.16 and 4.92 kJ mol-1, respectively. Some thermodynamic functions were derived from the present data, and the numerical tables were given.