Hydrothermal synthesis and luminescence properties of NaGd(WO4)2: Eu3+ phosphors
- Abstract
- Eu3+ doped and undoped NaGd(WO4)2 phosphors were synthesized via a facile one-step hydrothermal method without involving any surfactants or further heat treatment. X-ray powder diffraction, scanning electron microscope (SEM), fourier transform infrared spectroscopy (FTIR), decay curves, photoluminescence excitation and emission spectra were used to characterize the NaGd(WO4)2: Eu3+ phosphors. It was found that the pH value has a crucial effect on the synthesis of NaGd(WO4)2. The well-crystallized NaGd(WO4)2 crystals can only be obtained under an appropriate pH range of 5~9. Meanwhile, the morphology properties were studied, results show that the morphology of NaGd(WO4)2 changes with the pH value goes by, and it is time-dependent under proper pH=7 which may bring us a new insight into the growth of NaGd(WO4)2 crystals and raise a new way for the fine controlling and designing of other crystals. Also, the luminescence properties of Eu3+ doped NaGd(WO4)2 were discussed. The high emission quantum efficiency and suitable color coordination of NaGd(WO4)2:Eu3+ phosphors suggest the material could be a promising phosphor for generating white light in phosphor-converted white light emitting diodes(WLEDS).
- Issued Date
- 2014
- Awarded Date
- 2014. 8
- Type
- Dissertation
- Publisher
- 부경대학교
- Affiliation
- 대학원
- Department
- 대학원 의생명융합공학협동과정
- Advisor
- Seo Hyo Jin
- Table Of Contents
- Abstract vi
1. Introduction 1
2. Theoretical background 4
2.1. A brief introduction to luminescence 4
2.2. Optical properties and energy level splitting of the 4f6 configuration of Eu3+ ions 6
2.3. Calculation of lifetime 8
2.4. Introduction of hydrothermal method 9
2.4.1. Instrumentation in hydrothermal processing of non-materials 9
2.4.2. Features of hydrothermal synthetic reactions 13
2.5 Crystal structure of NaGd(WO4)2 16
3. Sample preparation and experimental measurements 17
3.1. Starting materials 17
3.2. Synthesis of the samples 18
3.3 Characterization 21
4. Results and discussion 22
4.1. Identification of the as-prepared samples 22
4.2. Effect of the Eu3+ concentration 24
4.3. Effect of the pH 26
4.4.Formation mechanism for the sheet-like NaGd(WO4)2 phosphors 31
4.5. Luminescence properties 37
4.5.1. Excitation and emission spectra 37
4.5.2. Decay cruves 43
4.5.3. Charge transfer transition and chromatic properties of the NaGd(WO4)2:Eu3+ samples 45
4.5.4. Calculation of Judd-Ofelt (J-O) intensity parameter Ωλ and quantum efficiency of the 5D0 level 50
4.5.5. Thermal quenching of luminescence 55
5. Summary and conclusions 64
6. References 66
7. Acknowledgement 72
- Degree
- Master
- Appears in Collections:
- 대학원 > 의생명융합공학협동과정
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