Effects of Eu2+ substitution on structural and optical properties with blue light emission in pollucite CsAlSi2O6 phosphor

Abstract A series of Eu2+ substituted pollucite [(Cs1-xEu1-2x)AlSi2O6 (CASO:xEu) (x = 0.001–0.08)] phosphors were synthesized by a high-temperature solid-state reaction method in a reducing atmosphere and characterized by X-ray diffraction, photoluminescence (PL), and PL excitation (PLE) measurements. Under excitation at 275 nm, CASO:xEu phosphors exhibit an emission band that shifts from the bright blue region with color coordinates of (0.159, 0.247) to the bright blue-green region with color coordinates of (0.225, 0.421) with increasing x. Such tunable luminescence color was attributed to the crystal field splitting effect of Eu2+ ions because the substitution of Eu2+ created vacancies at Cs sites, and fluctuations occurred at the positions occupied by the Eu2+ ions. Studies on the temperature dependence of luminescence for x = 0.01, 0.03 0.05, and 0.07 in CASO:xEu reveal that 92.5%, 85.3%, 74.9%, and 79.8% of the initial value of the luminescence intensity at 300 K are retained at 400 K, respectively. Tuning the emission spectra was possible by varying the value of x while maintaining a high thermal stability.