화학공학소재연구정보센터
Thermochimica Acta, Vol.364, No.1-2, 23-33, 2000
Thermodynamic properties of 1D and 2D polymerized fullerite C-60 between 0 and 340 K at standard pressure
The temperature dependence of heat capacity of one-dimensionally (1D) and two-dimensionally (2D) polymerized C-60 produced by heating monomeric C-60 UP to 550 K at a pressure of 5 GPa and to 960 K at st pressure of 3.5 GPa, respectively, with the subsequent quenching of the samples to normal conditions has been studied in the 5-340 K range using the adiabatic vacuum calorimeter. The experimental objects were structurally identified as orthorhombic (1D) and tetragonal (2D, with some amount of 2D rhombohedral phase) crystalline modifications of polymerized C-60 We extrapolated the experimental temperature dependence of heat capacity C-p(0) down to 0 K and from this dependence we have calculated the following thermodynamic functions over the 0-340 K interval, enthalpy H-0(T) - H-0(0), entropy S-0(T) - S-0(0) and Gibbs function G(0)(T) - H-0(0). Assuming that S-0(0) = 0, we have estimated the standard entropies of formation Delta S-f(0) for studied 1D and 2D polymers and entropies of hypothetical transitions, occurring at T = 298.15 K and standard pressure, from monomeric C-60 to 1D and 2D polymers, as well as of the mutual transition between 1D and 2D phases under the same physical conditions.