Electronic structures of Mg3Pn2 (Pn=N, P, As, Sb and Bi) and Ca3N2 calculated by a first-principle pseudopotential method

Electronic structure calculations for Mg3N2, Mg3P2, Mg3As2 (low and high temperature modifications), Mg3Sb2, Mg3Bi2, and Ca3N2 have been performed. Mg3Sb2 is predicted to be an indirect semiconductor with the gap value of about 0.41 eV. Mg3As2 with a high temperature modification is also predicted to be a semiconductor with the gap value of about 1.1 eV, but the valence band maximum and the conduction band minimum of Mg3Bi2 contacts at Γ which would make it a semimetal. Mg3N2, Mg3P2, and Mg3As2 (low temperature phase) are semiconductors with the direct band gaps of 1.64 eV, 1.73 eV, and 1.57 eV, respectively. Ca3N2 is a semiconductor with a gap of about 1.2 eV.