Low-temperature heat capacity of pentlandite

The heat capacity of synthetic pentlandite Fe4.60Ni4.54S8 was measured over the temperature range 6-306 K. Experimental values of C-p (T) indicate tha t there are no phase transitions. The thermodynamic functions C-p (T), H(T) - H(0), and S(T) - S(0) were evaluated: C-p (298.15) = 442.7 J/mol .K, S(2 98.15) - S(0) = 474.9 J/mol .K, and H(298.15) - H(0) = 76280 J/mol (molar m ass: 779.877 g). Below 10 K, the heat capacity of pentlandite fits the regr ession C-p(T) = a T + b T-3. The linear term is typical of metals and known as an electronic contribution to the heat capacity. This agrees with the h ypothesis that there is metal bonding among cations in tetrahedral sites.