| Popis: |
The temperature dependences of the heat capacity C p° = f(T) were studied in an adiabatic vacuum calorimeter for the orthorhombic, tetragonal, and rhombohedral polymeric C60 phases in the 7—340 K temperature interval with an error of ∼0.2%. Comparative analysis of C p° of these phases formed by stacking of one-dimensional and two types of two-dimensional polyfullerenes C60, was performed, and their fractal dimensionalities D were determined for temperatures below 50 K. The thermodynamic functions of the crystalline polymeric C60 phases were calculated in the temperature region from O → 0 to 340 K: C p°(T), H°(T) — H°(0), S°(T) — S°(0), and G°(T) — H°(0). Assuming that S°(0) = 0, the standard entropies of formation Δf S° of these phases from graphite at T = 298.15 K and standard pressure were calculated. In addition, the entropies of transformation of the initial face-centered cubic phase of fullerite C60 in the crystalline polymeric C60 phases and entropies of their interconversions under the same conditions were estimated. The thermodynamic characteristics of the polymeric C60 phases were reviewed. |
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