Calculation of phase diagrams of the Li₃N-Al system for AlN growth

To investigate the possibility of AlN synthesis from Li₃N and Al as source materials, a phase diagram of the Li₃N-Al system was constructed by using calculation of the phase diagram (CALPHAD) method. Thermodynamic data of a ternary system was prepared on the basis of data of binary systems, which are Al-Li, Al-N and Li-N. In the present work, we newly incorporated thermodynamic data of Li₃AlN₂ into the system. Gibbs energy function of Li₃AlN₂ is described by a stoichiometric compound model and the parameter was determined to reproduce our experimental results. The calculated phase diagram was verified by differential thermal analysis (DTA). The calculated solution temperature of Li₃AlN₂ agreed with the DTA results and the validity was confirmed.