Decomposition of MgSiN 2 in nitrogen atmosphere

Abstract

Magnesium silicon nitride MgSiN 2 was prepared by direct nitridation of Si/Mg 2Si/Mg/Si 3N 4 powder compact in a temperature range 1350–1420 °C. The thermal stability examination showed that MgSiN 2 is stable up to 1400 °C at 0.1 MPa N 2 pressure. The activation energy of decomposition of MgSiN 2 calculated from the temperature dependence of mass loss in the range of 1400–1650 °C is Δ H = 501 kJ mol −1. The time dependence and nitrogen pressure dependence of MgSiN 2 decomposition was also investigated at constant temperature. MgSiN 2 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 MgSiN 2 was calculated in a temperature range 25–2200 °C.