Thermodynamic assessment of the Si–N system

Motivated by the thermodynamic assessment of the Ga–N and In–N binaries, the thermodynamic parameters of the Si–N system are optimized in a similar way. The intermetallic compound Si3N4 is treated as stoichiometric and the terminal solution phase diamond_Si as the pure diamond_Si. The liquid solution phase is assumed to be a substitutional solution with Redlich–Kister formula for the expression of its excess Gibbs energy. The fugacity of nitrogen is considered when describing the behavior of the gas phase, especially with high pressure. The complete T–x phase diagram for the Si–N binary system is given. In this optimization a consistent thermodynamic data set for the Si–N system is obtained by means of CALPHAD (CALculation of PHAse Diagrams) method. The calculation results agree well with experiments.