Role of crystal defects in red long-lasting phosphorescence of CaMgSi2O6:Mn diopsides
Role of crystal defects in red long-lasting phosphorescence of CaMgSi2O6:Mn diopsides
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DOI：
10.1039/c2jm32953k
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发表时间：
2012-01-01
影响因子：
--
通讯作者：
Gourier, Didier
中科院分区：
文献类型：
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作者：
Bessiere, Aurelie;Lecointre, Aurelie;Gourier, Didier
CaMgSi2O6:Mn透透苷用于体内持久磷光（LLP）成像。研究了LLP机制中涉及的捕获缺陷。在1100℃Ar-H-2气氛下退火Mn掺杂透辉体时，Ca EXAFS/XANES和电子顺磁共振（EPR）证实了顺磁氧空位，而x射线衍射、Mn XANES和EPR显示了SiO2的形成和Mn掺杂物的显著蒸发。在475 K处发现了一个归因于氧空位电子捕获的热激发发光（TSL）峰，导致了rt处的LLP。适合体内成像的最强烈的红色LLP是通过在高Mn-II含量（有利于Mn-Mg（II）红色而不是Mn-Ca（II）橙色发光）和有利于LLP的氧空位的形成和发光产光率之间的权衡实现的。Mn XANES显示Mn- ii的有效电荷大于2+，符合空穴陷阱在LLP机制中的作用。在Ar-H-2中较低温度（800℃和900℃）退火的化合物显示出较小的粒径（60 ~ 70 nm）和最大的Mn含量，但由于表面淬火缺陷导致发光和LLP较差。
CaMgSi2O6:Mn diopsides are used for in vivo long-lasting phosphorescence (LLP) imaging. Trapping defects involved in the LLP mechanism were investigated. On annealing Mn-doped diopsides at 1100 degrees C in an Ar-H-2 atmosphere, Ca EXAFS/XANES and electron paramagnetic resonance (EPR) evidenced paramagnetic oxygen vacancies while X-ray diffraction, Mn XANES and EPR revealed SiO2 formation and significant evaporation of the Mn dopant. A thermally stimulated luminescence (TSL) peak at 475 K ascribed to electron trapping at oxygen vacancies was found responsible for LLP at RT. Most intense red LLP suitable for in vivo imaging was achieved by a trade-off between a high Mn-II content (favourable to Mn-Mg(II) red over Mn-Ca(II) orange luminescence) and the formation of oxygen vacancies favourable to LLP and luminescence light yield. Mn XANES revealed an effective charge larger than 2+ for Mn-II, in line with the role of hole trap in the LLP mechanism. Compounds annealed at lower temperatures (800 degrees C and 900 degrees C) in Ar-H-2 showed smaller particle size (60-70 nm) and maximum Mn content but poor luminescence and LLP due to surface quenching defects.