The role of Ln3+ (Ln = Eu, Yb) in persistent red luminescence in MgGeO3:Mn2+
The role of Ln3+ (Ln = Eu, Yb) in persistent red luminescence in MgGeO3:Mn2+
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DOI：
10.1039/c7tc03151c
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发表时间：
2017-09-14
影响因子：
6.4
通讯作者：
Tanabe, S.
中科院分区：
文献类型：
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作者：
Katayama, Y.;Kayumi, T.;Tanabe, S.
本文采用固相反应技术制备了Mn2+和Ln(3+) （Ln = Eu, Yb）共掺杂的MgGeO3荧光粉，并对其光学性能进行了研究。由于Mn2+离子在紫外（UV）激发下发生T-4(1) -> (6)A(1)跃迁，Mn2+掺杂样品在红色区域表现出持续发光，在677nm处达到峰值。基于Eu3+的电荷转移（CT）跃迁和带隙能，构建了二价镧系基态相对于导电带和价带边缘的能级图。DE(Ln), （Ln = Eu, Yb）分别为0.95和0.52 eV，代表二价镧系基态与导带底部之间的能隙。与Mn2+单掺杂样品相比，Mn2+-Eu3+共掺杂样品和Mn2+-Yb3+共掺杂样品的热释光（TL）发光曲线在约502 K和332 K处分别显示出一个额外的TL发光峰，陷阱深度（E-trap）分别为1.49和0.99 eV。陷阱与DE（Ln）的对应表明Eu3+和Yb3+本身在MgGeO3: Mn2+荧光粉中起电子陷阱的作用。我们还证明了Mn2+-Eu3+共掺杂材料由于其更深的陷阱深度，可以成为具有光刺激功能的长期体内成像的良好探针。
In this paper, Mn2+ and Ln(3+) (Ln = Eu, Yb) co-doped MgGeO3 phosphors were prepared using a solid state reaction technique, and their optical properties were investigated. Mn2+-doped samples exhibit persistent luminescence in the red region, peaking at 677 nm, because of the T-4(1) -> (6)A(1) transition of the Mn2+ ions under ultraviolet (UV) excitation. Based on the charge transfer (CT) transition of Eu3+ and the band-gap energy, energy level diagrams with divalent lanthanide ground states relative to the conduction and valence band edges were constructed. DE(Ln), (Ln = Eu, Yb), which represents the energy gaps between the divalent lanthanide ground states and the bottom of the conduction band, were found to be 0.95 and 0.52 eV, respectively. Compared to a Mn2+ singly-doped sample, the thermoluminescence (TL) glow curves of the Mn2+-Eu3+ co-doped sample and the Mn2+-Yb3+ co-doped sample showed an additional TL glow peak at approximately 502 and 332 K with trap depths (E-trap) of 1.49 and 0.99 eV, respectively. The correspondence of Etrap with DE(Ln) suggests that Eu3+ and Yb3+ themselves work as electron traps in the MgGeO3: Mn2+ phosphors. We have also demonstrated that the Mn2+-Eu3+ co-doped material could be a good probe with photo-stimulated functions for long-term in vivo imaging owing to its deeper trap depth.