Synthesis and photoluminescence properties of near-UV pumped novel Sm3+ doped β-LiAlSiO4 phosphor for red-orange LEDs

Abstract

The series of novel Li(1−x)AlSiO4:xSm3+ (x = 0.005, 0.01, 0.02, 0.03 and 0.04 mol) phosphors were prepared by traditional solid state method at 900 °C. The crystalline phase of β-eucryptite (LiAlSiO4) sample was verified by X-ray diffraction (XRD) analysis. Moreover, scanning electron microscopy (SEM) and EDAX was investigated for morphological and for content present in the as-prepared sample. On the SEM analysis, the average particle size was in the range of 2–10 μm. The photoluminescence (PL) excitation (λem = 602 nm) and emission (λex = 402 nm) of Li(1−x)AlSiO4:xSm3+ were investigated. The optimum PL intensity was observed at 602 nm (4G5/2 → 6H7/2). However, because of symmetric nature of Sm3+ doped β-LiAlSiO4 phosphor gives more PL intensity at 565 nm (4G5/2 → 6H5/2) as compared to 650 nm (4G5/2 → 6H9/2) due to quartz channel structure of β-LiAlSiO4. The concentration quenching was observed at 0.03 mol concentration of Sm3+ ions in β-LiAlSiO4 due to energy transfer. The CIE color coordinates (x = 0.595, y = 0.387) clearly indicated that the phosphor LiAlSiO4:Sm3+ can be used as a potential candidate for the phosphor-converted red-orange light emitting diodes under near-UV (n-UV) excitation.