Nano-scale study of microstructure of Eu(DBM) 3 phen-doped poly(methyl methacrylate) by near-field scanning microscopy a
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Xiaohong Sun Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
Qijin Zhanga) Structure Research Laboratory and Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui, 230026, People’s Republic of China
Hai Ming Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
Jianhua Cao School of Mechatronic Engineering, Beijing Institute of Technology, Beijing, 100081, People’s Republic of China
Zengchang Li, Biao Chen, Jie Xu, and Hui Zhao Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China (Received 15 October 2003; accepted 11 March 2004)
Eu(DBM)3phen-doped poly(methyl methacryate) (PMMA) with different doping concentration were prepared. The highest doping concentration sample (10000 ppm) was examined by near-field scanning optical microscopy (NSOM) with a resolution of 50 nm; and the result showed that there were no aggregates larger than 50 nm in the doped polymer. This result was further confirmed by optical properties of the doping material. Concentration quenching was not detected by metastable-state lifetime measurements, indicating that no aggregates existed. According to the fluorescence spectra analysis, the relative intensity ratio (R) of 5D0→7F2 to 5D0→7F1 transition was not shown to be significantly changed with the increasing of Eu3+ content. The analysis reflected that the local structure and asymmetry in the vicinity of europium ions were not changed, and that the Eu3+ ions in PMMA were homogeneously dispersed.
I. INTRODUCTION
In recent years, rare earth ions containing polymers have attracted much attention for their potential application for luminescence and laser systems.1–3 The main reason these have so much potential is that polymerbased rare earth luminescent materials can be processed easily, a fact that is advantageous for optical and electronic applications (such as polymer waveguides, polymer light-emitting diodes, and active polymer optical fiber).2,3 Technological advances have been limited by the amount of rare earth ions introduced via doping without a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2004.0326 2256
http://journals.cambridge.org
J. Mater. Res., Vol. 19, No. 8, Aug 2004 Downloaded: 28 Mar 2015
causing phase separation in conventional inorganic crystals or glass.4 In addition to that limitation, the concentration quenching of rare earth-doped inorganic crystals or glass usually sets at relatively low concentrations (approximately 1000 ppm-wt).5 However, encapsulating rare earth ions with organic ligands makes it possible to incorporate them into polymer hosts up to higher concentrations (approximately 1 wt%).5 It is well-known that a relative higher doping concentration usually induces concentration quenching and the existence of fractal clusters, which are deleter
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