“…Three investigations of equilibrium vapor pressures in the system have been reported. Viksman and Gordienko used Knudsen effusion/mass spectrometry to determine p P 2 in equilibrium with Ni 3 P and elemental nickel; for the reaction,
Δ G ° was −73 887 J/mol at 1744 K and −79 306 J/mol at 1761 K. Biltz and Heimbrecht measured the partial pressure of P 4 in equilibrium with NiP 3 /NiP 2 and NiP 2 /Ni 5 P 4 mixtures; for the reaction,
Δ G ° was +3125 J/mol at 870 K and +969 J/mol at 917 K. (It should be noted that NiP 3 is not stable at these temperatures in Figure ; this further emphasizes the tentative nature of the diagram.) For the reaction,
Δ G ° was +2957 J/mol at 1034 K.…”