Cl− skeleton modification and K+ charge compensation construct Eu2+ subcrystalline luminescent structure in NaAlSiO4

Abstract

In this work, the highly homogeneous NaAlSiO4 structure was constructed by glass relaxation crystallization method. The evolution of the subcrystalline luminescence structure was examined by using Eu2+ as a structural probe. The optimization of luminescent properties and phase structure changes of Cl− substitution, Eu2+ occupancy and K+ charge compensation were studied by XRD, EDS, PL spectra, PLE spectra and luminescence thermal stability analysis. The research revealed the AB layer spacing of the crystal stretched and the hexatomix ring opened by Cl− directionally replace O2−(O5), inducing more Eu2+ to selectively occupy the Na+(I) site, resulting in local charge defects in the lattice. The transition emission efficiency of Eu2+ was increased by 50 % with introducing K+ for directional charge compensation. In comparison with NaAlSiO4:2%Eu2+, the NaAlSiO3.96Cl0.04:2%Eu2+-8K+ phosphor showed a 20.82 % increase in ΔE, indicating improved thermal sensitivity in this phosphor series, which holds promising potential for application in LED devices.