Composition-dependent thermal and thermomechanical properties of spinel-type MgAlON from density functional calculation

As ceramics based on magnesium aluminum oxynitrides solid solutions are promising materials as refractories, windows/armors, phosphors, and so forth, it is essential to explore their thermal and thermomechanical properties, owing to the physical requirements on application. In this study, Mg5xAl23-5xO27+5xN5-5x were chosen for the investigation on composition-dependent thermal and thermomechanical properties by the theoretical calculations. Though the binary system with octahedral bonds contributes more to the thermal expansion coefficient of Mg5xAl23-5xO27+5xN5-5x, the binary system with tetrahedral bonds plays an important role in the variation of the thermal expansion coefficient. The change of heat capacity with the rise of x is mainly attributed to the variation of covalent character of Mg5xAl23-5xO27+5xN5-5x. Moreover, the thermal conductivity is mainly affected by the scattering from atoms in 8a sites. Both thermal and mechanical properties contribute to the variation of thermomechanical properties of Mg5xAl23-5xO27+5xN5-5x. This study can provide guidance to designing spinel materials with desirable thermal and thermomechanical properties for application.