Highly enhanced luminescence of Sr S i 2 O 2 N 2 : E u 2+ phosphors by Mg 2+ substitution and their application in pc‐LED

The effect of substitution of Sr 2+ by Mg 2+ on the luminescence properties of (Sr 0.9 −  x Mg x )Si 2 O 2 N 2 :0.1Eu 2+ were investigated as a function of the concentration of Mg 2+ ( x ). The peak position of the yellowish green emission from (Sr 0.9 −  x Mg x )Si 2 O 2 N 2 :0.1Eu 2+ was invariant with x . However, the luminescence intensity was significantly affected by x . With increasing Mg 2+ concentration, the intensity increased to a maximum at x  = 0.1. Partial substitution of Sr 2+ by Mg 2+ enhanced the intensity 1.8‐fold. The Eu 2+ concentration affected the peak positions of both luminescence and excitation. With increasing Eu 2+ concentration, the red‐shifting and enhancement of the luminescence were associated with the nephelauxetic effect. Concentration quenching of the luminescence occurred above y  = 0.07 in the (Sr 0.8 −  y Mg 0.1 )Si 2 O 2 N 2 : y Eu 2+ . Above the critical concentration of Eu 2+ , non‐radiative transitions between adjacent Eu 2+ ions were more effective than the nephelauxetic effect. Optimized (Sr 0.83 Mg 0.1 )Si 2 O 2 N 2 :0.07Eu 2+ phosphors were fabricated with blue GaN LED and the chromaticity index of the phosphor‐formulated GaN LED was investigated as a function of the wt% of the optimized phosphor.