Mechanism of the prolongation of the green afterglow of SrAl₂O₄:Dy³⁺ caused by the use of H₃BO₃ flux

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• 作者：Bao-gai Zhai^a ; Long Yang^a ; Qing-lan Ma^b ; Xianyun Liu^a ; Yuan Ming Huang^a ; ^{dongshanisland@126.com" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Phosphors ; Afterglow ; Photoluminescence ; Density functional calculation ; Band structure
• 刊名：Journal of Luminescence
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：181
• 期：Complete
• 页码：78-87
• 全文大小：3794 K

文摘

Significant prolongation in the green afterglow of SrAl₂O₄:Dy³⁺ was achieved by adding 10 mol% H₃BO₃ into the starting material. The surface morphology, crystalline structure, chemical composition, photoluminescence, afterglow and decay characteristics of the phosphor were characterized by scanning electron microscopy, X-ray diffractometry, energy-dispersive X-ray spectroscopy, transmission electron microscopy, photoluminescence and photoexcitation spectroscopy, respectively. It was found that the afterglow time constant of the green afterglow from SrAl₂O₄:Dy³⁺ phosphor could be enhanced over 100 folds from 53 to 5538 s after the addition of 10 mol% H₃BO₃ flux. No traces of Eu were found in the phosphors within the 1 μg/g detection limit of the inductively coupled plasma atomic emission spectrometry. By employing meta generalized gradient approximation to describe the exchange–correlation functional, the band structures of SrAl₂O₄:Dy³⁺ were calculated within the framework of density functional theory. The ground state of Dy³⁺ ions and the defect levels of height="14" width="21" alt="View the MathML source" style="margin-top: -5px; vertical-align: middle" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S0022231316304719-si0001.gif">$V_O^{••}$, height="17" width="19" alt="View the MathML source" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S0022231316304719-si0002.gif">$V_{Sr}^{″}$ and height="17" width="20" alt="View the MathML source" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S0022231316304719-si0003.gif">$V_{Al}^{″\prime }$ were quantitatively determined in the band gap of SrAl₂O₄. A possible afterglow mechanism was proposed to shed fresh light on the green afterglow of SrAl₂O₄:Dy³⁺. The significant prolongation in the afterglow of SrAl₂O₄:Dy³⁺ can be attributed to the H₃BO₃ flux introduced height="17" width="20" alt="View the MathML source" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S0022231316304719-si0003.gif">$V_{Al}^{″\prime }$ in the host lattice.