Thermal quenching of Eu²⁺ emission in Ca- and Sr-Ga₂S₄ in relation with VRBE schemes

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• 作者：A. Dobrowolska^a ; ^b ; B. Dierre^a ; ^{B.F.P.R.Dierre@tudelft.nl} ; C.M. Fang^c ; H.T. Hintzen^a ; P. Dorenbos^a ; ^{P.Dorenbos@tudelft.nl}
• 关键词：SrGa2S4 ; CaGa2S4 ; Thiogallate ; VRBE ; Thermal quenching
• 刊名：Journal of Luminescence
• 出版年：2017
• 出版时间：April 2017
• 年：2017
• 卷：184
• 期：Complete
• 页码：256-261
• 全文大小：744 K
• 卷排序：184

文摘

Structural and optical properties of MGa2S4 (M = Mg, Zn, Ca, Sr, Ba) compounds have been compared, and the vacuum referred binding energy (VRBE) schemes were constructed for the lanthanide ions in the iso-structural compounds CaGa2S4 and SrGa2S4 employing literature data. The VRBE of an electron in the 5d excited state of Eu2+ was found at 0.75 and 0.97 eV below the bottom of the conduction band (CB) in CaGa2S4:Eu and SrGa2S4:Eu, respectively. Such differences explains the unexpected higher thermal quenching temperature reported for Eu2+-doped SrGa2S4 (T50% = ∼475 K) compared to Eu2+-doped CaGa2S4 (T50% = 400 K) The significantly lower VRBE at the CB-bottom in CaGa2S4 versus SrGa2S4 may be explained by the shorter Ga-S bond lengths in SrGa2S4.