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理学院数学物理进展论坛——Investigation of Eu doped silicate ap

更新日期:2016-11-28 作者:macg 浏览次数:319


报告题目:Investigation of Eu doped silicate apatite phosphors for LED applications

报告人:Marco Kirm,教授(博士),爱沙尼亚塔尔图大学校长

报告时间:2016年12月2日早上 9:00

报告地点:理学院三楼会议室(S310)

报告摘要:

    Development of novel phosphors for white light generation using light emitting diodes (LEDs) is an active research area due to such advantages1 over other light sources as high efficiency, low power consumption, long service life, compact size etc. Silicates with apatite structure have a high potential for LED phosphor applications because of their stability and high efficiency.2,3,4 We investigated luminescence properties of silicate apatites M2Ln8(SiO4)6O2 (where M = Mg, Ca, Sr; Ln = Y, La), pure and doped with Eu3+ ions (0.5-2.0 at. %). Ceramics were prepared by high-temperature solid-state reaction using precursors synthesized under hydrothermal conditions. Some samples were annealed in H2/Ar reducing atmosphere in order to convert Eu3+ into Eu2+ and to evaluate compounds with coexisting 4f-4f and 5d-4f transitions.

    The complex structure of silicate apatites offers good opportunities for material engineering. There are two crystallographic sites in the IXA14VIIA26(SiO4)6O2 structure5, which can be occupied by the alkaline earth (M2+) and rare earth (Ln3+) cations, they are 9 and 7-fold coordinated for A1 and A2 sites, respectively. Small radius Mg2+ ions and larger Sr2+ occupy preferentially the A2 and A1 sites, respectively, which results in some differences in luminescence properties of Eu-doped Mg-based and Sr-based apatites. Medium size Ca2+ ions seem to populate mainly A1 sites and properties of Eu luminescence in Sr- and Ca-based apatites are similar. The excitation mechanisms in the energy range from visible-to-VUV and the properties of observed emissions (4f and 5d luminescence of rare earths, intrinsic and defect emissions of hosts) including decay kinetics were analyzed taking into account the peculiarities of apatite structure. The potential of Eu-doped silicate apatite phosphors for LED applications will be discussed.

References:

1. Feldmann, C.; Jüstel, T.; Ronda, C.R.; Schmidt, P.J. Adv. Funct. Mater., 2003, 31, 511-516.

2. Shen, Y.; Chen, R.; Gurzadyan, G. G.; Xu, J.; Sun, H.; Khor K. A.; Dong, Z. Opt. Mater. 2012, 34, 1155-1160.

3. Sokolnicki, J.; Zych, E. J. Lumin. 2015, 158, 65-69.

4. Yuan, S.; Wang, L.; Cui, Z.; Yang, Y.; Zeng, H.; Cheviré, F.; Tessier, F.; Chen, G. J. Mater. Sci. & Appl. 2015, 1, 33-37.

5. Blasse, G. J. Solid State Chem. 1975, 14, 181-184.

报告人简介:

    演讲人Marco Kirm是爱沙尼亚塔尔图大学校长/物理所教授,拉托维亚科学院外籍院士,爱沙尼亚国家研究策略委员会成员,爱沙尼亚智能控制委员会成员。其研究兴趣主要聚焦在传奇的可被应用在白光LED和闪烁体等上的宽禁带半导体材料(含尺度调控如纳米级),同时也覆盖基本光动力学研究中的物理问题。现其已在Physical Review B等国际顶级期刊上发表SCI论文234篇(论文被他引近2757次,H指数28),主持欧盟国际框架型项目如COST计划等3项以及15项爱沙尼亚国家自然科学基金项目,同时其也是多个欧盟国际学术会议如LUMDETR的轮值主席。由于其在促进波罗的海国家科学联合发展的贡献,于2013年获得波罗的海合作发展奖章一枚。

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