Decomposition of MgSiN2 in nitrogen atmosphere

Magnesium silicon nitride MgSiN2 was prepared by direct nitridation of Si/Mg2Si/Mg/Si3N4 powder compact in a temperature range 1350–1420 °C. The thermal stability examination showed that MgSiN2 is stable up to 1400 °C at 0.1 MPa N2 pressure. The activation energy of decomposition of MgSiN2 calculated from the temperature dependence of mass loss in the range of 1400–1650 °C is ΔH = 501 kJ mol−1. The time dependence and nitrogen pressure dependence of MgSiN2 decomposition was also investigated at constant temperature. MgSiN2 is stable at 1560 °C in 0.6 MPa nitrogen atmosphere. Using these experimental data together with the heat capacity published in a literature the Gibbs energy of formation of MgSiN2 was calculated in a temperature range 25–2200 °C.