Structural, electronic, magnetic and optical properties of CaO induced by oxygen incorporation effects: A first-principles study

•O-incorporated CaO systems are structurally stable.•CaO is a paramagnetic insulator material with a band gap of 6.25 eV.•Predicted systems exhibit the half-metallic nature.•The magnetism is produced mainly by the oxygen spin-up state.•Optical properties are enhanced by the oxygen incorporation. Density functional theory (DFT)-based calculations of the structural, electronic, magnetic, and optical properties of CaOx (x = 1, 2 and 3) have been carried out to investigate the effect of oxygen incorporation in CaO. The newly created CaO2 and CaO3 compounds exhibit good structural stability. CaO is a paramagnetic material, showing the insulator nature with a band gap of 6.25 eV. The formation of the new materials may induce the half-metallicity resulting from the insulator spin-up state and metallic spin-dn state, the corresponding spin-up band gaps of 9.52 and 11.01 eV are obtained in CaO2 and CaO3, respectively. Moreover, the magnetism is also induced with the total magnetic moments of 2 and 4 μB, respectively, which are produced mainly by the asymmetric O-2p orbitals. Incorporating the oxygen atoms into the CaO crystal structure makes possible the absorption of the visible and ultraviolet lights, with the absorption coefficient reaching values of the order of 105 (cm−1). Results obtained herein suggest that the oxygen incorporation in CaO may form new materials with novel properties suitable for providing the highly polarized electrons in spintronic devices, as well as prospective applicability in the optoelectronic technology.