The Characteristics and Applications of YPO4 and YVO4 Nanoscaled Phosphors Prepared by the Chemical Co-precipitation Method

• Main Authors: Meng-Han Tasi, 蔡孟翰
• Other Authors: Hao-Ying Lu
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/fgx46t

碩士 === 國立金門大學 === 電子工程學系碩士班 === 103 === There are two topics in this research. First one is the white-light phosphors consisting of Dy3+ doped yttrium phosphate (YPO4) and Dy3+ doped YP1-XVXO4 were prepared by chemical co-precipitation method in this research. After the 1200℃ thermal treatment in the air atmosphere, the white-light phosphors with particle sizes around 90 nm can be obtained. In order to reduce the particle size of phosphors, the alkaline-washing method was applied to the original synthesis process. The phosphors with the alkaline-washing process possess smaller particle sizes around 65 nm. From the X-ray Diffraction (XRD) patterns, the phosphors with different thermal-treatment temperatures all possess tetragonal structures. The lattice constant of YP1-XVXO4 increases with the proportion of vanadium ion(x) and trends to the lattice constant of yttrium vanadate (YVO4). In the photoluminescence excitation (PLE) spectra, there are four absorption peaks observed in the YPO4-based phosphors. These peaks are resulted from the following electron transitions, 325nm : 6H15/2→4K15/2, 352 nm : 6H15/2→4M15/2+6P7/2, 366 nm : 6H15/2→4I11/2, and 390 nm : 6H15/2→4M19/2, the 352 nm peak is the strongest absorption peak. Besides, the emission peaks of wavelength 484 nm and 576 nm can be observed in the photoluminescence (PL) spectra. These two peaks originate from the electron transitions 4F9/2→6H15/2 and 4F9/2 →6H13/2, respectively. In our research, the phosphor based on YPO4 with 0.8% Dy3+ possesses the strongest PL intensity and its CIE coordinate locates at the blue-light area. In order to obtain the white-light phosphors, the vanadium ions were applied to substitute the phosphorus ions to compose YP1-XVXO4. From the PL spectra, the strongest PL intensity can be obtained with 30% vanadium ions. As the concentration of vanadium ions increases to 40%, the phosphors with the CIE coordinates locating at the white-light area can be obtained. And the other one, a nano-composite film can emit blue light with 484 nm wavelength was produced in this research with low-temperature process, and this film can be used to produce yellow-light lighting devices on glass substrates or to the yellow-light LED array to form a white-light lighting device. In first step, chemical co-precipitation method was applied to produce YVO4:Dy nanoparticles size are around 60 ~ 90 nm. From photoluminescence spectra (PL), light with 484 nm wavelength was observed and it is resulted from the electron transition 4F9/2 → 6H15/2. And then, a SiO2-film colloidal precursor was prepared in the second step by mixing ethanol, distilled water, hydrochloric acid and tetraethoxysilane (TEOS) with suitable mole ratio. Then YVO4:Dy nanoparticles were dispersed in the colloidal precursor and the mixed colloidal precursor was coated on a substrate by spin coating. After the above processes, the glass substrate with the mixed colloidal film was placed in a furnace to process a thermal treatment 200℃ and a nano-composite film emits 484 nm wavelength with 600 nm thickness can be obtained.