Novel red-emitting Ca2LiScB4O10: Sm3+ phosphor for WLED: Photoluminescence, thermal stability, crystal structure, Judd-Ofelt parameters and energy band gap studies

Abstract

In this paper, a novel red-emission Ca2LiScB4O10: Sm3+ phosphor system has been synthesized by a high-temperature solid-state reaction method. 50–100 nm well-distributed monoclinic Ca2LiScB4O10: Sm3+ (space group of P21/n) was confirmed by Transmission electron microscopy and SAED patterns. Rietveld refinement PXRD pattern revealed that the doping of different amounts of Sm3+ ions expanded the lattice constants/volume and shifted the most intense diffraction peaks to a larger angle side with shoulders. The changes in coordination groups and crystal structure of Ca2LiScB4O10 have been observed from the Fourier transform infrared spectra, the 11B nuclear magnetic resonance, and O1s and B1s X-ray photoelectron spectroscopy. The increase of Sm3+ doping amounts decreased the energy band gap which matched well with the density functional theory simulation. The studies on the crystal structure and Rietveld refinement indicated that the Sm3+ occupied both the Ca2+ and Sc2+ sites. The photoluminescence performances such as the excitation/emission spectra, CIE diagram, decay lifetime, and thermal stability have been systematically investigated. The photoluminescence behaviors have been explained by Judd-Ofelt cross-section, branching ratio, color temperature, quantum efficiency, and lifetime. The energy level of Sm3+ and the emission and thermal quenching mechanism were discussed. 0.7%Sm phosphor exhibited significant pure and strong reddish emission at 600 nm and this phosphor is promising for WLED device application.