Photoluminescence characterization of (Y,Gd)(V,P)O4:Eu3+ phosphor and the effects of Sc3+ and Bi3+ addition

다국어 초록 (Multilingual Abstract)

(Y,Gd)(V,P)O₄:Eu^(3+) and Sc- or Bi-added (Y,Gd)(V,P)O₄:Eu^(3+), which could be potential red-emitting components for cold cathode fluorescent or light emitting diodes, were prepared by a solid-state reaction. The crystalline phases of the prepared phosphor powders were identified using an X-ray diffraction system. The morphology and the particle size of the phosphors were characterized by SEM. The photoluminescence properties of the phosphors under the excitation of ultraviolet ray were investigated. In both cases, the concentration of Eu activator exhibiting maximum emission intensity was 10 mol%. The photoluminescence results showed that the optimum chemical compositions of the phosphors are (Y_(0.5)Gd_(0.4)Eu_(0.1))(V_(0.8)P_(0.2))O₄, (Sc_(0.05)Y_(0.45)Gd_(0.4)Eu_(0.1))(V_(0.8)P_(0.2))O₄ and (Bi_(0.05)Y_(0.45)Gd_(0.4)Eu_(0.1))(V_(0.8)P_(0.2))O₄. The XRD results indicated that these phosphors have a single phase of tetragonal structure with space group I4₁/amd, which is identical to the crystal structure of YVO4. The (Y_(0.5)Gd_(0.4)Eu_(0.1))(V_(0.8)P_(0.2))O₄ phosphor showed higher emission and better chromaticity characteristics compared to commercial Y₂O₃:Eu^(3+) red phosphor. It was shown that the addition of Sc^(3+) improves the color purity of the (Y_(0.5)Gd_(0.4)Eu_(0.1))(V_(0.8)P_(0.2))O₄ phosphor. It was further shown that the band edge of the excitation spectra with increasing Bi^(3+) is shifted toward the longer wavelength region. The temperature dependence of the emission intensity of the (Y_(0.5)Gd_(0.4)Eu_(0.1))(V_(0.8)P_(0.2))O₄ phosphor was also evaluated in the range of room temperature to 150℃.

목차 (Table of Contents)

• Chapter 1. Introduction = 1
• Chapter 2. Literature Survey = 5
• 2-1. Cold cathode fluorescent lamp = 5
• 2-2. White LED = 8
• 2-3. Phosphor = 10
• 2-3-1. Phosphors for CCFL = 10
• 2-3-2. Phosphors for white LED = 11
• Chapter 3. Experiments = 13
• Chapter 4. Results and Discussion = 16
• 4-1. Composition optimization of (Y,Gd)(V,P)O₄:Eu^(3+) phosphor = 16
• 4-2. Effect of Sc^(3+) addition = 34
• 4-3. Effect of Bi^(3+) addition = 41
• Chapter 5. Conclusions = 48
• References = 49