Effect of Tb3+ ion concentration on photoluminescence and thermoluminescence studies of Y4Al2O9 phosphor

Abstract

Herein Tb3+ (0.1, 0.2, 0.5, 1, 1.5, 2 and 2.5 mol %) doped Y4Al2O9 (monoclinic phase of yttrium aluminium oxide Y/Al 2:1) phosphors have been synthesized by conventional modified solid state reaction method (CMSSRM) using inorganic materials like Yttrium Oxide (Y2O3), Aluminium Oxide (Al2O3), Terbium Oxide (Tb2O3) and boric acid as a flux. The prepared phosphor samples were characterized using X-ray diffraction analysis (XRD), photoluminescence (PL), and thermoluminescence (TL) glow curve. From the XRD data, using the Scherrer formula the calculated average crystallite size of Tb3+ doped Y4Al2O9 phosphor is around 235 nm. Photoluminescence excitation spectra show sharp excitation peak centred at 270 nm and broad excitation peak centred at 300 nm which is due to charge transfer band. Here emission spectra show three distinct peaks centred at 492 nm (5D4 → 7F7), 544 nm (5D4 → 7F6) and 584 nm (5D4 → 7F4). Results indicate that PL intensity increases with increasing the concentration of doping ion i.e. Tb3+ up-to 2 mol % after that due to concentration quenching PL intensity decreases. Commission Internationale de l'Éclairage (CIE) values were calculated as X = 0.24 and Y = 0.56 and it shows intense green emission. TL glow curves were analysed with effect of doping ion concentration and effect of variable UV exposure time. Kinetic parameters were calculated using various methods proposed by Chen and others.