Effect of lattice distortion induced by Li+ doping on white light CaWO4: Dy3+ phosphors: Phase, photoluminescence and electronic structure

Abstract

A series of Dy3+ doped CaWO4 phosphors was successfully synthesized via the facile high temperature solid state method. The phase purity and effect of different valence isomorphism on cell parameters were fully evaluated by XRD analysis. When divalent Ca2+ is replaced by trivalent Dy3+, the local electric field is distorted, which has an obvious influence on the lattice. The introduction of Li+ aggravates the degree of lattice distortion. The excitation spectra of CaWO4: Dy3+ and CaWO4: Dy3+, Li+ have the same shapes, but they are some different in intensity. The emission spectra show that the co-doping of Li+ can reduce the luminescence intensity at 575 nm, and many phosphors emit white light by adjusting the Dy3+ doping concentration. The density of states (DOS) and charge difference plots of phosphors were studied by first-principles calculation. The calculated results show that the band gap decrease gradually on doping.