Synthesis and characterization of blue-light and yellow-light emitting phosphors via sol-gel method.
| Autor: | Chung-Tao Chen, 陳崇道 |
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| Rok vydání: | 2005 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 93 This thesis investigated the synthesis and characterization of BaMgAl10O17:Eu2+ (BAM), Sr2CeO4 and Sr3SiO5:Eu2+ phosphors. The blue-light emitting BAM was synthesized via the sol-gel route using citric acid and ethylene glycol. Emission of blue-light (453 nm) was obtained from these phosphors. The luminescent intensity increased as the temperature of heat treatment was increased. The increasing molar ratio of ethylene glycol to citric acid (φ) led to an increase in rate of BAM phase formation at low temperature (1100℃). The variation of φ value resulted in the change of sol-gel reaction mechanism and microstructure of powders. Secondly, Sr2CeO4 was prepared via sol-gel route using citric acid and ethylene glycol. The blue emission (470 nm) was obtained under an excitation of 282 nm. The cathodoluminescent emission (471 nm) under excitation at both low (5 kV) and high (10 kV) acceleration voltage was also observed. Moreover, the sol-gel route resulted in the uniform grain structure and homogeneous composition, which led to enhance luminescent intensity. The significant decrease in the luminescence of Sr2CeO4 was observed when the heating temperature was above 1000℃ for solid state route and 1200℃ for sol-gel route respectively. This decrease is due to the fact that Sr2CeO4 decomposed at high temperature and formed SrCeO3. Finally, Sr3SiO5:Eu2+ phosphor was studied. This material was prepared via the sol-gel route using tetraethyl orthosilicate as precursor. The yellow-light emission at 470 nm was obtained. Sr3SiO5:Eu2+ exhibited a broad excitation band from Near-UV to blue-light region. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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