Mechanism for bifurcation of broadband luminescence spectra from Ce 3+ ions at dodecahedral sites in garnets {CaY 2 }[M 2 ](Al 2 Si)O 12 (M = Al, Ga, Sc)

Autor: Qiuhong Zhang, N.M. Khaidukov, N.Yu Kirikova, Rui Shi, I.A. Zhidkova, Hongbin Liang, Vladimir N. Makhov
Rok vydání: 2018
Předmět:
Zdroj: Dyes and Pigments. 148:189-195
ISSN: 0143-7208
DOI: 10.1016/j.dyepig.2017.09.012
Popis: Cerium doped CaY 2 Al 4 SiO 12 , CaY 2 Ga 2 Al 2 SiO 12 and CaY 2 Sc 2 Al 2 SiO 12 garnet phosphors have been synthesized by using a high temperature solid-state reaction method and studied by optical spectroscopy techniques in the wide temperature range. It has been revealed that the emission spectra from all the synthesized samples can be well represented as the sum of spectral bands due to the 5d - 4f transitions of two optical Ce 3+ centers having different local environment. It is proposed that these two centers arise due to various types of distortions caused by crystal chemical differences between calcium and yttrium ions located at the dodecahedral crystallographic site in the garnet structure. Such a dual-mode distortion site leads to increasing the Stokes shift of Ce 3+ emission spectra for the studied garnets in comparison with YAG:Ce 3+ . The phosphor CaY 2 Al 4 SiO 12 :Ce 3+ shows a weak blue shift of Ce 3+ luminescence compared to YAG:Ce 3+ and demonstrates excellent thermal stability on temperature quenching effects by manifesting the thermal quenching temperature T 1/2 at 635 K. Substitution of Al 3+ by larger cations Ga 3+ or Sc 3+ has resulted in the additional blue shift of the luminescence spectrum and the appearance of strong thermal quenching.
Databáze: OpenAIRE
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