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Effects of Post Calcination Treatment on Photoluminescence and Structural Properties of Scheelite-type LiEuW2O8 Nanocrystals Synthesized by Glycothermal Reaction

Published online by Cambridge University Press:  01 February 2011

Ryo Kasuya ,
Tetsuhiko Isobe ,
Shinobu Yamao  and
Hocine Sfihi
Ryo Kasuya
Affiliation:
y12433@educ.cc.keio.ac.jp, Keio University, Faculty of Science and Technology, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama, 2238522, Japan, +81-45-566-1544
Tetsuhiko Isobe
Affiliation:
isobe@applc.keio.ac.jp, Keio University, Faculty of Science and Technology, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan
Shinobu Yamao
Affiliation:
shinobu.yamao@si.idemitsu.co.jp, Idemitsu Kosan Co. Ltd., 1280, Kamiizumi, Sodegaura, 299-0293, Japan
Hocine Sfihi
Affiliation:
Hocine.Sfihi@espci.fr, UMR CNRS 7142, Laboratoire de Physique Quantique, ESPCI, 10 rue Vauquelin, Paris, 75231, France
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Abstract

The scheelite-type LiEuW2O8 (LEW) nanoparticles of ∼50 nm in diameter were synthesized from lithium acetate, europium (III) acetate and phosphotungstic acid in 1,4-butylene glycol at 300°C for 2h by autoclave treatment. Post calcination treatment at 600°C for 2 h enhanced the photoluminescence at 465 nm due to the 4f - 4f transition excitation of Eu3+ by a factor of 24.4, and due to charge transfer (CT) excitation from either O2− or WO42− to Eu3+ by a factor of 5.8. Convergent beam electron diffractmetry and the compositional analysis revealed the non-stoichiometric structure of the scheelite-type LEW nanocrystals. Raman spectroscopy also detected the WO4 vibrational modes due to the tetragonal scheelite-type LEW. Solid-state 7Li single pulse excitation MAS NMR indicated the existence of at least three Li sites in the samples. We conclude that the following three factors are improved by calcination to increase the f-f transition probability of Eu3+: (i) a distribution of the Eu3+ – Eu3+ distance, (ii) the symmetry of Eu3+ polyhedra, (iii) the symmetry of tetrahedral WO4 units in the vicinity of Eu3+ polyhedra. Furthermore, oxygen is provided for non-stoichiometric LEW during calcination to enhance the CT probability.

Keywords

nanostructureoptical propertieshydrothermal
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 951: Symposium E – Nanofunctional Materials, Nanostructures and Novel Devices for Biological and Chemical Detection , 2006 , 0951-E03-29
Copyright
Copyright © Materials Research Society 2007

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References

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