화학공학소재연구정보센터
Journal of Chemical Thermodynamics, Vol.31, No.12, 1523-1536, 1999
Thermodynamic properties of iron silicides FeSi and alpha-FeSi2
The molar heat capacities of FeSi and alpha-FeSi2 have been determined by low-temperature adiabatic calorimetry at temperatures between T = 11 K and T = 400 K. From the heat capacity data the derived thermodynamic functions; standard molar enthalpy Delta(0)(T)H(m)(o), standard molar entropy Delta(0)(T)S(m)(o), and Gibbs energy function Phi(m)(o) = Delta(0)(T)S(m)(o) - Delta(0)(T)H(m)(o)/T were calculated. Standard molar entropies of (45.57 +/- 0.50) J . K-1 . mol(-1) and (68.31 +/- 0.71) J . K . mol(-1) at T = 298.15 K for FeSi and alpha-FeSi2, respectively, have been found. In an optimization procedure, the standard molar enthalpies of formation Delta(f)H(m)(o) were calculated using our measured data and data calculated from (iron + silicon) melts. The values obtained are: for FeSi, Delta(f)H(m)(o)(298.15 K) = -73.89 kJ . mol(-1) and for alpha-FeSi2, Delta(f)H(m)(o)(298.15 K) = -78.62 kJ . mol(-1).