Thermodynamic properties and phase equilibria in the silicon-phosphorous system

Knudsen effusion mass spectrometry and a static method were used to study the vapor composition and the thermodynamic properties of the Si-P melt with the phosphorous content from 0.09 to 26.5 at.% in the temperature range 1507 to 1831 K. A representative file of experimental data comprising about 100 values of phosphorus activity at various concentrations and/or temperatures was obtained. The thermodynamic characteristics as functions of temperature and concentration were approximated by the ideal associated-solution model under the assumption that SiP and Si2P complexes exist in the melt. The boundaries of the region of liquid phase stability on the phase diagram were computed, and agreement with the available experimental information was obtained.