THERMODYNAMIC INVESTIGATION OF THE MANGANESE-TELLURIUM SYSTEM

Two intermetallic compounds (MnTG2.03 and MnTe) have been investigated using potentiometry and differential scanning calorimetry. The following cell was used : (-) Mn / RbCl + LiCl + MnCl2 (melt) / MnxTe1-x (+) and potentiometric measurements were performed in the temperature range 590 < T/K < 750 and in the manganese molar fraction range 0.10 < X(Mn) < 0.515. Molar heat capacities of solid MnTe2.03 and MnTe compounds were measured in the temperature range 323 K - 703 K and 323 K - 773 K respectively. Using these results the following values of the molar Gibbs free energy and molar entropy of formation of the two intermetallic compounds have been calculated: Mn0.33Te0.67 DELTAG(o,f)(m,298 K) = 42.5 +/- 0.2 kJ.mol-1 DELTAH(o,f)(m,298 K) = 41.8 +/- 0.6 kJ.mol-1 DELTAS(o,f)(m,298 K) = 2.6 +/- 1.7 J.K-1.mol-1 Mn0.50Te0.50 DELTAG(o,f)(m,298 K) = -55.6 +/- 0.2 kJ.mol-1 DELTAH(o,f)(m,298 K) = -53.3 +/- 0.8 kJ.mol-1 DELTAS(o,f)(m,298 K) = 8.0 +/- 1.7 J.K-1.mol-1