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Polymer-Assisted Annealing of Spray-Pyrolyzed Powders for Formation of Luminescent Particles with Submicrometer and Nanometer Sizes

Authors

  • Wei-Ning Wang,

    1. Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, Higashi Hiroshima 739-8527, Japan
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  • Soon-Gil Kim,

    1. Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, Higashi Hiroshima 739-8527, Japan
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  • I. Wuled Lenggoro,

    1. Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, Higashi Hiroshima 739-8527, Japan
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    • *Present address: Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, Tokyo 184-8588, Japan.

  • Kikuo Okuyama

    Corresponding author
    1. Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, Higashi Hiroshima 739-8527, Japan
      †Author to whom correspondence should be addressed. e-mail: okuyama@hiroshima-u.ac.jp
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  • J. Ballato—contributing editor

  • This work was supported in part by NEDO's Nano-technology Particle Project funded by the Ministry of Economy, Trade, and Industry (METI), and Grants-in-Aid from the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) of Japan.

†Author to whom correspondence should be addressed. e-mail: okuyama@hiroshima-u.ac.jp

Abstract

Phosphor nanoparticles (e.g., SrTiO3:Pr,Al and (Y,Gd)3Al5O12:Ce) were prepared using a conventional spray pyrolysis method in conjunction with a polymer-assisted heat treatment (annealing). The effects of spray/annealing temperatures, polymer type, polymer concentration, and salt addition on the morphology, crystallinity, particle/crystal size, and the photoluminescence intensity of as-prepared as well as annealed phosphor particles were investigated. The results showed that the nanocrystal growth of as-prepared-sprayed submicrometer particles was improved and that the nanocrystal networks disintegrate into nanoparticles when polymer or salt solutions are added during the heat-treatment process. The additional combustion heat and gas evolution during the thermal reaction of polymer appear to be the main reasons for this. On the contrary, only compacted agglomerated particles rather than dispersed nanoparticles were found in the case of annealing without polymer/salt addition.

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