Thermodynamic properties of $\mathrm{Si}$–$\mathrm{P}$ melts

The Knudsen mass spectrometry and static method are used to investigate the composition of vapor and thermodynamic properties of silicon–phosphorus melts in the temperature range from $1507$ to $1831$ K and in the range of compositions of $0.09$ to $26.5$ at. $\%\mathrm{P}$. About a hundred values of activity for phosphorus are obtained with different compositions and/or temperatures. The thermodynamic functions of liquid $\mathrm{Si}$–$\mathrm{P}$ alloys are approximated using the model of ideal associated solutions with two associates $\mathrm{SiP}$ and $\mathrm{Si}_2\mathrm{P}$. The limits of stability of the liquid phase in the diagram of state for the $\mathrm{Si}$–$\mathrm{P}$ system are calculated on the basis of the obtained thermodynamic data and their model description. Good agreement is observed between the calculation results and the available experimental data.