Cerium-doped LaSi 3 N 5 : Computed electronic structure and band gaps

First-principle calculations are performed using VASP to enhance the understanding of the electronic structure of stoichiometric LaSi3N5 and Ce-doped LaSi3N5. Electronic structure and band gaps are calculated using DFT and the screened Coulomb hybrid functional HSE06. Five doping schemes are investigated: La3+/*Ce3+, La3+/□ (□=cation vacancy), La3+/Ce3+, La3+/Ce2+ compensated by one framework N3−/O2− substitution, and combined La3+/Ce3+and La3+/□ substitutions. The vacancy is electronically balanced by N3−/O2− substitutions. Two pseudopotential files for CeIII are used to investigate the effect of f orbitals on the calculated band gap. There was no change in the calculated value of the band gap using DFT method for the *CeIII doped LaSi3N5 compared to the stoichiometric LaSi3N5 (3.15eV). HSE06 provided more precise band gaps. The calculated band gap of Ce-doped LaSi3N5 is 4.65eV with the possible electronic transitions from Ce spin-up 4f to Ce spin-up 4f states, or La 5d states..