First-principles calculations: Structural stability, electronic structure, optical properties and thermodynamic properties of AlBN2, Al3BN4 and AlB3N4 nitrides

In this work, using first-principles calculations based on density functional theory were performed to predict the structural stability, electronic structure, optical properties and thermodynamic properties of three nitrides (AlBN2, Al3BN4 and AlB3N4). The calculated formation enthalpies of AlBN2, Al3BN4, and AlB3N4 are -5.369, -6.108, and -5.630 eV/atom, respectively, suggesting that the structures of these three nitrides are stable. By calculating the phonon spectrum and phonon density of states, it can be known that the three nitrides are dynamically stable. The electronic structure data reveal that the band gaps of AlBN2, Al3BN4, and AlB3N4 are 3.35, 3.05, and 3.59 eV, respectively. The polycrystalline and directional optical properties are discussed, and the AOPT of AlBN2 is [0.99, 0.99], indicating its optical anisotropy. Finally, a detailed examination of thermodynamic parameters reveals that Al3BN4 has the most stable thermodynamic properties, and the order of stability is: Al3BN4 > AlB3N4 > AlBN2.