Improvement of the luminescent properties of molybdate base red phosphors

• Main Authors: Chung-lin Chen, 陳長麟
• Other Authors: Yung-Der Juang
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/18897643040455901995

碩士 === 國立臺南大學 === 材料科學系碩士班 === 101 === In this research, we use solid-state reaction methods to synthesize a serier of molybdate red phosphor. The crystal structure, luminescence properties and the morphology of molybdate red phosphor was analysised by x-ray diffraction, fluorescence spectrophotometer, scanning electron microscope and microscopes Raman spectrometer. XRD data shows that the molybdate phosphors are single phase with a tetragonal scheelite structure. From the result of fluorescence spectra, there is a strong absorption peak at 394 nm and 465 nm and a strong red radiation at 616 nm. In the part of different calcination temperatures, the samples sintering at 900℃ for 5 hours have the best luminous intensity. For Yttrium doping effect, yttrium nitrate has better results in optimum intensity, when the doping concentration is about 50 %. Since both Y and Eu are trivalent ions, the divalent Ca ion replaced by Y and Eu which will cause charge imbalance affects the luminous efficiency. In this reseach, we achieve the charge compensation by doping monovalent metal ions (Li+, Na+, K+), the results showed that the charge compensation emission intensity increases, especially for Na+. According to these results, we can see that phosphor luminescence properties can be improved by charge compensation. In the other part of complex molybdate phosphor, 2 % silicon doping concentration in molybdate has the best optimum intensity, it also improves the 394 nm and 465 nm intensity ratio, which have a good matching with near ultraviolet and blue LED chips. According to the results, we can see that molybdate red phosphor is a good choice for white LED applications.