J. Korean Ceram. Soc. > Volume 52(1); 2015 > Article
 Journal of the Korean Ceramic Society 2015;52(1): 66. doi: https://doi.org/10.4191/kcers.2015.52.1.66
 Synthesis of NaY(WO4)2:Ho3+/Yb3+ Phosphors via The Microwave-Modified Sol-Gel Route and Their Upconversion Photoluminescence Properties Chang Sung Lim Department of Advanced Materials Science & Engineering, Hanseo University ABSTRACT $NaY_{1-x}(WO_4)_2:Ho^{3+}/Yb^{3+}$ 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 synthesized via the cyclic microwave-modified sol-gel route; their upconversion properties were investigated. Well-crystallized particles showed a fine and homogeneous morphology with particle sizes of $2-5{mu}m$. Under excitation at 980 nm, the synthesized particles exhibited yellow emissions based on a strong 550-nm emission band in the green region and a very strong 655-nm emission band in the red region. The Raman spectra of the doped particles indicated the domination of strong peaks at higher and lower frequencies induced by the incorporation of the $Ho^{3+}$ and $Yb^{3+}$ elements into the $Y^{3+}$ sites in the crystal lattice, which resulted in unit cell shrinkage that accompanied a new phase formation of the $WO_{4-x}$ group. Key words: Microwave sol-gel, Phosphors, Yellow emission, Upconversion, Raman spectroscopy
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