First-Principles Investigations of the Physical Properties of Magnesium Nitridoboride

In this article, we investigate the electronic, dielectric, dynamic, and elastic properties of new magnesium nitridoboride (MgNB9) using a first-principles approach based on density functional theory. No available experimental or theoretical investigations of these physical properties have been previously reported in the literature. Our work shows that MgNB9 is a semiconducting positive uniaxial trigonal material with an indirect band gap (Z-L) of 1.76 eV and mixed ionic-covalent character. In addition, its electronic dielectric tensor is nearly isotropic, and the magnitude of its components is similar to those reported for ferroelectric materials. By contrast, its static dielectric tensor is strongly anisotropic in the plane orthogonal to its optical axis. This anisotropy is mainly governed by a highly polar low-frequency mode assigned to localized Mg motions. Furthermore, this material is mechanically stable, and its bulk and shear moduli are larger than those reported on III-V semiconductors. These results suggest that MgNB9 could be a promising potential material for applications in optoelectronics.