Figures -21 The phase diagram iron-selenium

The composition of p-FeSe is approximately Fei 04Se and it has a homogeneity range extending from 49.0 atom-% to 49.4 atom-% Se. The phase is stable below 730 K. 

The heat capacity of (3-Fei 04Se was measured in the temperature range 5 to 350 K by Gronvold and Westrum [59GRO/WES]. The heat capacity and entropy values at 298.15 K are selected  

The heat capacity of a sample with the composition Fei,o4Se was measured in the temperature range 298 to 1050 K by Gronvold [68GRO] using adiabatic shield calorimetry. 

The Gibbs energy of formation is calculated from the selected enthalpy of formation and the standard entropies to be  

This value is included in Appendix E since it was calculated with a non-TDB auxiliary datum. 

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