Luminescence properties of Eu3+ ions doped in LaM2AlO5 (M = Ba, Sr) with disordered layer structure
- Abstract
- Red-emitting phosphors of Eu3+-doped LaM2AlO5 (M = Ba, Sr) were prepared by the Pechini-type sol-gel (PEG) method. The crystal structure was investigated by X-ray powder diffraction (XRD). The excitation, emission spectra and decay curves are reported. Excitation band of the Eu-O charge-transfer transition of Eu3+ in LaSr2AlO5 is observed at 314 nm. The band shifts for LaBa2AlO5:Eu3+ to low energy centered at 331 nm. The emission lines due to the 4f → 4f transition of Eu3+ are much broader in comparison with the lines of usual Eu-doped phosphors (e.g. Y2O3:Eu3+). The excitation spectra of the 7F0 → 5D0 transition is obtained by monitoring the 5D0 → 7FJ emission of Eu3+ in LaM2AlO5 (M = Ba, Sr). Emission spectra of selectively excited at the 5D0 levels show systematic changes in crystal-field splittings of the 5D0 → 7FJ (J = 1, 2) transition. The disordered nature of Eu3+ luminescence is discussed in relation with crystal structure of LaM2AlO5 (M = Ba, Sr).
- Issued Date
- 2012
- Awarded Date
- 2012. 8
- Type
- Dissertation
- Publisher
- 부경대학교
- Affiliation
- 부경대학교 대학원
- Department
- 대학원 물리학과
- Advisor
- 서효진
- Table Of Contents
- Abstract iii
1. Introduction 1
2. Theory and analysis 5
2.1 A brief introduction to luminescence 5
2.2 Optical properties and energy level splitting of the 4f6 configuration of Eu3+ ions 8
2.3 The introduction to crystal-field parameters and crystal-field strength 10
2.4 Crystal structure of LaSr2AlO5 14
3. Sample preparation and spectroscopic measurements 19
3.1 Chemical reagents, synthesis and X-ray diffraction phase analysis 19
3.2 Spectroscopic measurements 21
4. Result and discussion 23
4.1 Structure characterization 23
4.1.1 X-ray diffraction patterns of La1-xEuxSr2AlO5 23
4.1.2 X-ray diffraction patterns of LaSr2-xBaxAlO5:Eu3+ 25
4.2 Excitation and emission spectra 28
4.2.1 Luminescence spectra of LaSr2AlO5:Eu3+ 28
4.2.2 Luminescence spectra of solid solution LaSr2-xBaxAlO5: Eu3+ 35
4.3 The 7F0 → 5D0 excitation spectra and decays 39
4.4 Selectively excited emission spectra and crystal-field analysis of LaSr2-xBaxAlO5:Eu3+ 42
4.5 Doping mechanism and structural analysis 58
5. Conclusions 60
References 61
Acknowledgement 63
- Degree
- Master
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