Double substitution induced tunable photoluminescence in the Sr2Si5N8:Eu phosphor lattice

Abstract

A series of Sr_2−xLa_xSi_5−xAl_xN₈:Eu²⁺ nitride phosphors were synthesized by the gas-pressed sintering method. The influence of La³⁺–Al³⁺ incorporation into Eu²⁺-doped Sr₂Si₅N₈ phosphors on the crystal structure and luminescence properties was discussed in this work. X-ray diffraction with Rietveld refinements, photoluminescence spectra, thermal quenching behavior, and lifetimes were utilized to characterize the samples. More interestingly, an additional emission band located at lower-energy was observed under near-ultraviolet excitation, which is different from previous literature. Under the excitation of near-ultraviolet, the emission color for the La³⁺–Al³⁺ substitutions can be tuned from orange-red to red. The mechanism of the additional emission band located at lower-energy and the thermal quenching behavior are discussed too. This mechanism can efficiently tune optical properties, especially thermal stability, and could be general to luminescent materials.