Low temperature and pressureless synthesis of MgAlON: qualitative analysis and formation evolution

By calculating the Gibbs free energy of a magnesium aluminium oxynitride (MgAlON) system, pure MgAlON was obtained by pressureless sintering at 1 570 °C in a nitrogen atmosphere using Al, Al , and MgO as raw materials. The formation mechanism of MgAlON and phase evolution of the Al-Al -MgO-N system were investigated. The aluminium was melted at approximately 660 °C and formed AlN in the range 740- 1 250 °C. The reaction of AlN, Al , and MgO started to form a primary crystalline MgAlON phase at 950 °C, and as the temperature increased, the minerals continuously dissolved in the primary crystalline phase.