Study on the particle size control of green-emitting phosphor (Ba,Sr)2SiO4:Eu2+ via reduction firing using various flux agents

Tetsufumi Komukai, Masato Kakihana

Research output: Contribution to journalArticlepeer-review

Abstract

In this study, the particle size control of (Ba,Sr)2SiO4:Eu2+, a green-emitting phosphor, was evaluated via reduction firing using various flux agents. Phosphor particles grown to 31050 ¯m in diameter and having high internal quantum efficiency of 77.3% were obtained via reduction firing at 1473 K using 10 wt % BaCl2 as a flux. To reduce the particle size, the reduction firing temperature was lowered to 1223 and 1273 K respectively and the amount of BaCl2 was increased to 20 wt %. The diameter of phosphor particles significantly reduced; however, fibrous fine particles were formed and the internal quantum efficiency decreased to 60.7%. Using BaCl2KCl and BaCl2CsCl mixed fluxes to increase the amount of molten flux while suppressing the dissolution of (Ba,Sr)2SiO4 into the molten flux, a phosphor with fewer fibrous fine particles was obtained. In particular, the phosphor obtained via reduction firing at 1273 K using a 10 wt % BaCl210 wt % CsCl mixed flux had an improved internal quantum efficiency of 73.4%. The ionic radius of Cs+ (0.167 nm for CN = 6) is considerably larger than that of Ba2+ (0.135 nm for CN = 6) and Sr2+ (0.118 nm for CN = 6); therefore, high-quality host crystals with few defects could be possibly obtained without the substitution of Cs+ for Ba2+ and Sr2+ during reduction firing. To control the particle size of phosphor while maintaining a high internal quantum efficiency, the solubility of the host crystal into the molten flux as well as the substitution of the cation between the flux and host must be considered.

Original languageEnglish
Pages (from-to)1013-1018
Number of pages6
JournalJournal of the Ceramic Society of Japan
Volume126
Issue number12
DOIs
Publication statusPublished - 2018 Dec

Keywords

  • Flux
  • Green-emitting phosphor
  • Key-words: (Ba
  • Reduction firing
  • Sr)SiO:Eu

ASJC Scopus subject areas

  • Ceramics and Composites
  • Chemistry(all)
  • Condensed Matter Physics
  • Materials Chemistry

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