| Summary: | 碩士 === 國立交通大學 === 應用化學系所 === 92 === In this research we have successfully synthesized three series of Gd2O2S:R ( R = Tb3+, Pr3+, Eu3+) nanophosphors via a two-step process by utilizing simple hydrothermal apparatus at 140-200℃, followed by a annealing under H2S atmosphere at 500-1000℃. The correlation between phase purity, photoluminescence and microstructure of Gd2O2S:R nanophosphors were then characterized by X-ray diffraction, spectrofluorimeter, scanning microscope (SEM) and transmission microscope (TEM) techniques.
Our research indicates that the pH values and temperature adopted in the hydrothermal synthesis to form nanocrystalline Gd(OH)3 precursor are the most important processing parameters in determining the grain morphology and sizes of Gd2O2S:R nanophosphors. The morphology of nanocrystalline Gd(OH)3 precursor was observed to change from granular to rod-shaped when pH was allowed to vary from 8 to 10. The average diameter of granular Gd2O2S:R was found to be ca. 80 nm, whereas the aspect ratio (c/a) for Gd2O2S:R nano-rods was found to be 10 with length and diameter of 200 nm and 20 nm, respectively, as indicated by TEM investigations.
On the other hand, the luminescence and microstructure for bulk and nano-crystalline Gd2O2S:R phosphors prepared from solid-state and two-step hydrothermal routes, respectively, were also compared.
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