The Reaction of GaP ( s ) with H 2 O ( g ) and the Range of Stability of GaP ( s ) under Pressures of Ga2 O and P2

The reaction of with wet hydrogen has been studied by a vapor transport method. Experimental equilibrium constants in the temperature range of 800°–1100°C have been found to be in satisfactory agreement with the equilibrium constants calculated from the free energies of formation of the reacting components, , , and . A heat of formation of at 298°K of −42.75 kcal/mole has been obtained from the Knudsen cell measurements of Johnston. A value of for of 14.4 cal/deg mole has also been obtained. The range of pressures of and P2 over which is stable is described. Formation of both and is considered. Variation in the solubility of oxygen in as a function of the pressures of and P2 is discussed.