| Microwave-Modified Sol-Gel Process for Microcystalline KY(WO4)2: Ho3+/Yb3+ Phosphors and their Upconversion Photoluminescence Properties |
| Chang Sung Lim |
| Department of Advanced Materials Science & Engineering, Hanseo University |
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| ABSTRACT |
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$KY_{1-x}(WO_4)_2:Ho^{3+}/Yb^{3+}$ yellow phosphors with doping concentrations of $Ho^{3+}$ and $Yb^{3+}$ ($x=Ho^{3+}+Yb^{3+}$, $Ho^{3+}=0.05$, 0.1, 0.2 and $Yb^{3+}=0.2$, 0.45) were successfully prepared using the microwave-modified sol-gel method; their upconversion (UC) photoluminescence properties were investigated in detail. Well-crystallized particles, formed after heat-treatment at $900^{circ}C$ for 16 h, showed a fine and homogeneous morphology with particle sizes of $2-5{mu}m$. Under excitation at 980 nm, the UC $KY_{0.7}(WO_4)_2:Ho_{0.1}Yb_{0.2}$ and $KY_{0.5}(WO_4)_2Ho_{0.05}Yb_{0.45}$ particles exhibited excellent yellow emissions based on a strong 545-nm emission band in the green region and a very strong 655-nm emission band in the red region. Pump power dependence and Commission Internationale de L'Eclairage chromaticity of the UC emission intensity were evaluated. The spectroscopic properties were examined comparatively using Raman spectroscopy. |
| Key words:
Microwave sol-gel, Yellow phosphors, Upconversion, Raman spectroscopy |
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