- 著者
-
西須 佳宏
小林 幹男
竹内 理
- 出版者
- The Mining and Materials Processing Institute of Japan
- 雑誌
- 資源と素材 : 資源・素材学会誌 : journal of the Mining and Materials Processing Institute of Japan (ISSN:09161740)
- 巻号頁・発行日
- vol.119, no.9, pp.573-578, 2003-09-25
The effect of regents concentrations for recovery and shape of precipitate on the liquid-phase synthesis of precursor particles of Y<sub>2</sub>O<sub>3</sub> : Eu phosphor was studied. The amount of precipitant generated by hydrolysis of urea was remarkably changed by reaction temperature and initial concentration of urea. Therefore, the reaction rate of the precipitation reaction was controlled by reaction temperature and initial urea concentration. The recovery of precipitate was increased from < 10% to > 99% with the increase in urea concentration from 10 × 10<sup>-3</sup> to 30 × 10<sup>-2</sup> mol/dm<sup>3</sup> in the synthesis at 92°C for 1 hour, when initial concentration of rare-earth ion was 10 mmol/dm<sup>3</sup>. On the other hand, the particle size was decreased with increase in urea concentration. The shape of particles was changed from uniform sphere to irregular aggregate with increase in initial concentration of rare-earth ion under the lower urea concentration condition. However, mono-dispersed spherical particles were formed even in that case, when the ratio of rare earth for the urea was higher. Though non-aggregated particles were amorphous basic carbonate; (Y, Eu)OHCO<sub>3</sub>, the carbonate was crystallized in the aggregated particles. By the calcination at above about 600°C, both compositions converted to the oxide; (Y, Eu)<sub>2</sub>O<sub>3</sub>, but original shapes of precipitate particles were retained after that. Therefore, mono-dispersed spherical Y<sub>2</sub>O<sub>3</sub> : Eu phosphor particles could be obtained from morphologically identical precursors. These results indicate the range of initial reagents concentrations in which mono-dispersed spherical Y<sub>2</sub>O<sub>3</sub> : Eu phosphor is prepared.