Electronic structure and energy level schemes of RE3+:LaSi3N5 and RE2+:LaSi3N5−xOx phosphors (RE=Ce, Pr, ND, Pm, Sm, Eu) from first principles

摘要: Abstract First principles calculations of rare earth (RE)-doped LaSi 3 N 5 host lattice are performed to obtain the electronic structure, band gap (BG), and character transitions. Doping with both trivalent bivalent RE cations is inspected. 4f states form two bands occupied unoccupied separated by ~5 eV. In 3+ -doped compounds shifted ~6 eV more negative energies compared 2+ -compounds. This stabilization causes that in a different position relative valence conduction than therefore transitions apply. BG -compounds decreases from ~4.6 eV (Ce) ~1.5 eV (Eu). Except for Ce , exhibiting 4f→5d transition, other show charge transfer p→4f character. increases ~0.80 eV (Ce, Pr) ~0.95 eV (Nd, Pm), ~1.43 eV (Sm), ~3.28 eV (Eu) transition The energy level scheme constructed ab initio calculated structures agrees well experimental diagram. agreement demonstrates reliability hybrid functional HSE06 describe correctly nonbonding electrons.