Effect of Ga³⁺ and Gd³⁺ ions substitution on the structural and optical properties of Ce³⁺‐doped yttrium aluminium garnet phosphor nanopowders

Abstract

The structural and optical properties of commercially obtained Y Al O :Ce phosphor were investigated by replacing Al with Ga and Y with Gd in the Y Al O :Ce structure to form Y (Al,Ga) O :Ce and (Y,Gd) Al O :Ce . X-Ray diffraction (XRD) results showed slight 2-theta peak shifts to lower angles when Ga was used and to higher angles when Gd was used, with respect to peaks from Y Al O :Ce and JCPDS card no. 73-1370. This could be attributed to induced crystal-field effects due to the different ionic sizes of Ga and Gd compared with Al and Y . The photoluminescence (PL) spectra showed broad excitation from 350 to 550 nm with a maximum at 472 nm, and broad emission bands from 500 to 650 nm, centred at 578 nm for Y Al O :Ce arising from the 5d → 4f transition of Ce . PL revealed a blue shift for Ga substitution and a red shift for Gd substitution. UV-Vis showed two absorption peaks at 357 and 457 nm for Y Al O :Ce , with peaks shifting to 432 nm for Ga and 460 nm for Gd substitutions. Changes in the trap levels or in the depth and number of traps due to Ce were analysed using thermoluminescence (TL) spectroscopy. This revealed the existence of shallow and deep traps. It was observed that Ga substitution contributes to the shallowest traps at 74 °C and fewer deep traps at 163 °C, followed by Gd with shallow traps at 87 °C and deep traps at 146 °C. Copyright © 2016 John Wiley & Sons, Ltd.

Luminescence investigation of a cerium‐doped yttrium vanadate phosphor

“…Furthermore, the 4f 1 energy levels contained a doublet (2F 5/2 and 2F 7/2 ), which were the final states of fluorescence transition 5 d 1 →4 f 1 . Emission peaks at 546 nm and 574 nm were attributed to 5 d 1 –4 f 1 (2 F 5/2 ) and 5 d 1 –4 f 1 (2 F 7/2 ) transitions of the Ce 3+ ion . The shape of the spectra did not vary with Ce ion concentration, however the intensity varied completely for dopant concentrations.…”

Investigation of antimicrobial properties and in‐vitro bioactivity of Ce3+‐Sr2+dual‐substituted nano hydroxyapatites

“…As the crystal field splitting of the 5d energy levels of the Ce 3+ ion increases, the energy difference between the lowest 5d sublevel and the ground state of the 4f configuration of Ce 3+ becomes smaller and results in the slightly shifting of emission band toward longer wavelength (402 nm) (Figure 7). 54 In a similar way, Zhang et al 25 reported a tunable color change from blue to yellow, while investigating the luminescence properties of Ce 3+ , Mn 2+ -FAP under different UV excitation sources, for biolabeling application.…”

“…The emission from Ce 3+ is very sensitive and is affected by changes in the local lattice structure due to the resultant crystal field effects. 54 Hence, the peak position of the emission depends on the environment of the host matrix, which may bring about a blue shift in the Ce 3+ emission when co-activated with Sr 2+ . Because the ionic radii of Ce 3+ , Sr 2+ , and Ca 2+ (Ce 3+ (0.107 nm) < Sr 2+ (0.118 nm) > Ca 2+ (0.10 nm)), replacing Ca 2+ with Ce 3+ and Sr 2+ causes lattice expansion leading to an increase in the crystal field interaction of Ce 3+ .…”

Enhancement of the luminescence properties of Sr3(PO4)2:Dy3+,Li+ white‐light‐emitting phosphors by charge compensator Li+ co‐doping

“…The first method is combining a blue InGaN chip with a yellow phosphor (YAG:Ce). However, this kind of white LED has some shortcomings, such as high correlated colour temperature and low colour rendering index due to the lack of a red component . The second method is coating three primary colour (RGB) phosphors onto a near‐ultraviolet (UV) LED chip, but this approach gives poor luminous efficiency due to the interaction between different emissions .…”

“…However, this kind of white LED has some shortcomings, such as high correlated colour temperature and low colour rendering index due to the lack of a red component. [3,4] The second method is coating three primary colour (RGB) phosphors onto a near-ultraviolet (UV) LED chip, but this approach gives poor luminous efficiency due to the interaction between different emissions. [5] Thus, single component white-light-emitting phosphors with Eu 2+ -Mn 2+ co-doping have attracted much significant attention.…”