The phase diagram copper-selenium

Stelen, Fjellvag, Gr0nvold, Sipowska, and Westrum [96STO/FJE] measured the heat capacity of a-CuSe in the temperature range 5 to 653 K using adiabatic shield calorimetry. The heat capacity determined at 298.15 K is selected  

The Gibbs energy of formation of a-CuSe is calculated from the selected enthalpy of formation and entropy, the selected entropy of selenium and the entropy of copper in [89COX/WAG] yielding  

The enthalpy of transformation of the a P transition was determined to be A ,//° (CuSe, a P, 327 K) = (0.855 0.006) kJ-mof in [96STO/FJE]. The corresponding entropy change is (2.61 0.02) J-K -mol. Due to closeness of the transition and standard temperatures, selected values of the enthalpy of formation and entropy of P-CuSe were calculated by adding the enthalpy of transformation and the corresponding entropy to the values of the enthalpy of formation and the entropy of a-CuSe. The selected values are  

Gattow and Schneider [56GAT/SCH] determined the enthalpy of formation of Cu3Se2(cr) to be Af//° (Cu3Se2, cr, 298.15 K) = 98.9 kJ-moP using direct synthesis 

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Figure V-20 The phase diagram copper-selenium after Massalski [86MAS]. Reprinted from [86MAS], Copyright (1986), with permission from ASM International.

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