Synthesis and photoluminescence properties of (La1-xPrx)VO4 (x = 0~0.05) phosphor prepared using hydrothermal method

• Main Authors: Jia-Rong Jhang, 張家榮
• Other Authors: Yee-Shin Chang
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/um4dj4

碩士 === 國立虎尾科技大學 === 電子工程系碩士班 === 105 === In this study, LaVO4 was prepared by hydrothermal method to be the host material and doped with different concentrations of Pr3+ ion as the luminescent center for the phosphor. The effects of the Pr3+ ion concentrations and the annealing temperatures on the crystal structure and photoluminescence properties of the phosphor were investigated. Preparation of a series of LaVO4:Pr3+ phosphor, the XRD results show that the crystal structure of (La1-xPrx)VO4 phosphor performed using the hydrothermal method at 180°C for 16 h can be attributed to the tetragonal structure of LaVO4, and no secondary phases appear when the Pr3+ ion doping concentration increased. The SEM results show that the phosphor particles become larger and inconsistent as the Pr3+ ion concentrations increase. The Absorption analysis show that an absorption band between 200 ~ 330 nm is due to the lattice absorption, and the Pr3+ ion 4f-5d characteristic transition is located between in the 440 ~ 500 nm and 580 ~ 620 nm region. Under an excitation of 315 nm , the emission spectra show some emission bands appear which were corresponding to the 1D2→3H4、3P0→3H6 electron transition of Pr3+ ion, and the strongest emission appear when the Pr3+ ion concentration is 0.5 mol%. The CIE chromaticity coordinates varied from white light region to orange-red and then shift to blue region as the Pr3+ ion concentration increased. For Pr3+ ion-doped LaVO4 phosphor annealed at 600oC for 4 h, the XRD results show that the crystal structure keeps a tetragonal crystal structure. The SEM results show that phosphor particles were increased from 60 nm to 80 nm after annealing process, and the surface morphology gradually changed from reunion to uniform distribution. By 315 nm direct excitation, the main emission band still retains a series of LaVO4 doped with Pr3+ ion phosphor characteristics, belonging to the host luminescent, and the 1D2→3H4, 3P0→3H6 electron transition of the Pr3+ ion, respectively. When the Pr3+ ion concentration is 0.5 mol%, It possesses the strongest emission behavior, and is located in the near white light region with a CIE chromaticity coordinates of x=0.299, y=258. When annealing temperature increased, the crystal structure changes from a tetragonal to a monoclinic structure, and the surface morphologies of particle significantly larger and the reunion is more obvious. The emission spectra show the host luminescent gradually disappear, and the luminescence compositions change to the characteristic transition luminescence of Pr3+ ion corresponding to the 3P0→3H4, 3P0→3H5, 1D2→3H4, 3P0→3H6, 3P0→3F2 electron transition. It can be observed that the comparison to the monoclinic structure, tetragonal structure LaVO4 is a superior host material which possesses a higher luminous intensity.