Enhanced Emission from Li2CaSiO4:Dy3+ Phosphors by Doping with Al3+ and B3+

Abstract

Pure Li 2 CaSiO 4 , Li 2 CaSiO 4 :Dy 3+ and Al 3+ , B 3+ co-doped materials were prepared by a solid-state reaction in air at 900 o C for 6 h and characterized by using powder XRD. The luminescence properties of the synthesized phosphors were measured at room temperature with a spectrofl uorometer. Li 2 CaSiO 4 :Dy 3+ emits at 484, 575, and 660 nm upon 352 nm excitation. The emission spectrum intensity of Dy 3+ increased from 0.01 to 0.06 mol.%, and beyond 0.06 mol.%, concentration quenching was observed. Also, in this study, the effects of boric acid and aluminum oxide concentration on the photoluminescence properties of Dy 3+ doped phosphors were investigated. The results showed that boric acid and aluminum oxide were effective in improving the photoluminescence intensity of Li 2 CaSiO 4 :Dy 3+ compounds.Keywords: luminescence, X-ray diffraction, inorganic borate, aluminum oxide, boric acide.Introduction. Complex oxides involving silicates, aluminates, and borates have strong absorption in the VUV range, and for this reason they have been studied as host materials [1]. In particular, trivalent rare earth ion-doped borates have been widely studied for their applications as phosphors [2]. They are composed of an inert host lattice and an optically excited activator, typically a 3d or 4f electron metal. For applications in new full color fl at panel display industry, thermally stable, high luminous effi ciency, radiation resistant, fi ne particle size powders are required [3,4].Also inorganic phosphors containing rare earths have attracted great attention because of their extensive applications in fi elds such as information display, advanced laser materials and fi ber optical communication [5,6]. It is known that the luminescent properties of phosphors usually depend on the interactions with the environment around the activators in the host lattice [7]. The light-conversion phosphors for solid state lighting have attracted much attention in recent years [8]. Thus, authors and researchers have shown an increased interest in trivalent lanthanide (Ln 3+ )-doped luminescent materials because of their unique optical properties arising due to 4f transitions, which gives strong and sharp emissions [9]. Numerous papers have been published on luminescence properties of rare-earth phosphors [10-13].The orthosilicate matrix phosphors can be excited by UV and blue light, since these phosphors involve broad excitation bands. Dy 3+ rare-earth ions have a variety of optical energy level structures [14][15][16][17][18][19]. Therefore, the luminescence properties of Dy 3+ -doped inorganic crystal and glasses have been widely investigated.The aim of this work was to enhance the emission intensity of the Dy 3+ -doped Li 2 CaSiO 4 phosphor through doping H 3 BO 3 and Al 2 O 3 into the Ca 2+ site in the lattice. Recently, numerous researches reported the effect of co-doped Al 3+ and B 3+ cations on the luminescence properties of inorganic phosphors. For example, Silversimith et al., investigated the role of Al 3+ co-doping in improv...

High Catalytic Activity of Crystalline Lithium Calcium Silicate for Oxidative Coupling of Methane Originated from Crystallographic Joint Effects of Multiple Cations

“…Our recent research on various crystalline oxides revealed a significantly high OCM activity of a quasi‐ternary oxide Li 2 CaSiO 4 (Table ). This oxide was previously investigated as a host material of phosphorous, but its catalytic activity has never been reported. The OCM activity of Li 2 CaSiO 4 is found to be comparable to or even higher than that of the state‐of‐the‐art catalyst Mn−Na 2 WO 4 /SiO 2 .…”