Cubic γ-Be_3N_2: A superhard semiconductor predicted from first principles

摘要

The authors predict a superhard semiconductor phase of Be_3N_2 with cubic structure using first-principles calculations. The structural, mechanical, electronic, and optical properties of the Be_3N_2 have been investigated. Results indicate that the predicted Be_3N_2 phase is a wide gap semiconductor with a direct band gap of about 2.51eV. The calculated hardness of cubic γ-Be_3N_2 based on Mulliken overlap population analysis in first-principles technique approaches those of B_4C and B_6O. The higher mechanical property can be attributed to the existence of strong Be-N-Be covalent bond chains in the cubic structure. The obtained static dielectric constant of Be_3N_2 (4.6 eV) is close to the spinel structure of Si_3N_4 (4.7 eV).