Effect of Ho Co-Doping on the Long Lasting Emission of CaGa2S4:Eu

To investigate the long-lasting green afterglow from Ho added CaGa 2 S 4 :Eu compounds, photoluminescence (PL) and photoluminescence excitation (PLE) spectra are measured as a function of Ho concentration by keeping Eu one at 0.1 and 0.5 mol %. As Ho concentration increases, PL intensity of Eu decre...

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Bibliographic Details
Published in:Jpn J Appl Phys 2011-05, Vol.50 (5), p.05FG04-05FG04-3
Main Author: Hidaka, Chiharu
Format: Article
Language:eng ; jpn
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Summary:To investigate the long-lasting green afterglow from Ho added CaGa 2 S 4 :Eu compounds, photoluminescence (PL) and photoluminescence excitation (PLE) spectra are measured as a function of Ho concentration by keeping Eu one at 0.1 and 0.5 mol %. As Ho concentration increases, PL intensity of Eu decreases. PL from Ho at 660 nm has an additional broad excitation band ranging from 400 to 500 nm, emerging only if Eu 2+ ion is co-doped. Since this new band just coincides with the Eu 2+ emission in energy, electrons excited to the 5d states of Eu 2+ are considered to transfer to the Ho excited states, which are actually confirmed by the weakened Eu emission observed. In the decay curve of Eu emission in a co-doped sample, two long-lasting components are observed. Their lifetimes, however, steeply decrease when Ho concentration increases more than 1 mol %. In this paper, energy transfer between the two dopants is discussed.
ISSN:0021-4922
1347-4065
DOI:10.1143/JJAP.50.05FG04