K2LnZr(PO4)3 (Ln=Y, Gd and Eu) 형광체의 분광학 특성
- Alternative Title
- Optical Spectroscopy of K2LnZr(PO4)3 (Ln = Y, Gd and Eu) Phosphors
- Abstract
- Eu3+-doped K2LnZr(PO4)3 (Ln=Y, Gd and Eu) phosphors were synthesized by the solid state reaction method and their luminescent properties are investigated under the vacuum ultraviolet (VUV) and UV excitations. Crystalline phases of samples were confirmed by X-ray diffraction analyses. The patterns are in the good agreement with standard (JCPDS No. 49-0634). The Zr4+-O2- charge transfer (ZrCT) absorption band is observed at around 300 nm with band width of 100 nm. The broad emission band in the greenish-blue region with a maximum at 475 nm is attributed to the ZrCT transition in K2LnZr(PO4)3. Together with the broad Zr4+ emission band the strong Eu3+ emission lines are observed in the emission spectrum of K2LnZr(PO4)3 doped with Eu3+ ions. The excitation spectrum of the Zr4+ emission in K2EuZr(PO4)3 shows nearly the same spectral feature as that in K2YZr(PO4)3 and K2GdZr(PO4)3. The excitation spectrum due to the intra-4f transitions of Eu3+ is totally different from that of Zr4+ emission. The emission spectra and decay curves depend strongly on the excitation energy indicating that energy transfers occur by energy migration among the PO43- exciton states, ZrCT states, Gd3+ ions and Eu3+ ions. The decay of the Zr4+ emission band is remarkably decreased due to the increase of Eu3+ concentration at under excitation at 172 nm. The mechanism of broad band emission is based on ligand-to-metal charge transfer from the Zr4+-O2-. The energy transfer also occurs from ZrCT band to Eu3+ (M2) ions. The mechanisms are discussed in relation with structural properties of the K2LnZr(PO4)3 lattice. The emission color varies from greenish-blue to whitish with increasing Eu3+-content and the white-light emission is realized in single-phased phosphor of K2EuxGd1-xZr(PO4)3 (x=0.1) by combining the Zr4+ emission and the Eu3+ emission. All characteristics indicate that the K2LnZr(PO4)3 phosphors might have a potential application in lightings.
- Issued Date
- 2012
- Awarded Date
- 2012. 2
- Type
- Dissertation
- Publisher
- 부경대학교 대학원
- Alternative Author(s)
- Eun Sik Kim
- Affiliation
- 부경대학교
- Department
- 대학원 물리학과
- Advisor
- 서효진
- Table Of Contents
- Abstract.................................................................... xi
1. 서론...................................................................... 1
2. 이론적 배경............................................................ 5
2-1. 형광................................................................... 5
2-1-1. 형광 방출 및 방사 전이....................................... 5
2-1-2. 에너지 전달...................................................... 8
2-1-3. 전이확률과 열 소광............................................ 16
2-2. Closed-shell transition-metal complexes의 형광..... 19
2-2-1. Closed-shell 4+ 양이온 특성............................... 19
2-2-2. Ti4+-O2- 전이의 형광........................................ 19
2-2-3. Zr4+-O2- 전이 의 형광....................................... 21
2-2-4. Ce4+-O2- 전이 의 형광...................................... 23
2-3. K2LnZr(PO4)3의 결정 구조.................................... 24
2-4. 모체내의 Gd3+ 및 활성제 Eu3+의 광학적 특성........... 27
3. 실험방법................................................................ 31
3-1. 시료제작............................................................. 31
3-2. VUV 수명시간 측정............................................... 33
3-3. 레이저 분광학 실험............................................... 35
3-4. 방출 스펙트럼 및 수명시간 측정.............................. 37
4. 결과 및 논의........................................................... 38
4-1. K2LnZr(PO4)3 (Ln = Y, Gd, Eu)의 X-선 회절 분석.... 38
4-2. K2YZr(PO4)3의 XRD 구조검증과 결정 데이터............ 44
4-3. K2LnZr(PO4)3 (Ln = Y, Gd, Eu)의 여기 및 방출 스펙트럼.............................................................................46
4-3-1. K2LnZr(PO4)3 (Ln = Y, Gd, Eu)의 Zr4+-O2- 전하 전달 밴드......................................................................46
4-3-2. Eu3+가 첨가된 K2EuxLn1-xZr(PO4)3 (Ln = Y, Gd)의 여기 및 방출 스펙트럼..................................................50
4-3-3. Eu3+의 농도에 따른 K2LnZr(PO4)3의 (Ln = Y, Gd) 여기 및 방출 스펙트럼.....................................................54
4-3-3-1. Zr4+-O2-의 전하 전달 형광에 대한 여기 스펙트럼.............................................................................54
4-3-3-2. Eu3+ 방출형광 (5D0-7F2) 에 대한 여기 스펙트럼.............................................................................57
4-3-3-3. Eu3+ 전하 전달 밴드 (254 nm) 여기에 의한 방출
스펙트럼....................................................................60
4-3-3-4. Gd3+ 준위 (6LJ : 274 nm) 여기에 의한 방출 스펙트럼.............................................................................65
4-3-3-5. Gd3+ 준위 (6PJ : 313 nm) 여기에 의한 방출 스펙트럼.............................................................................69
4-3-3-6. Zr4+-O2-의 전하 전달 밴드 여기에 의한 방출
스펙트럼....................................................................73
4-3-3-7. Eu3+ 준위 (5L6 : 395 nm) 여기에 의한 방출 스펙트럼.............................................................................77
4-4. Eu3+을 첨가한 K2GdZr(PO4)3의 시간 적분 방출 스펙트럼
분석..........................................................................81
4-5. Zr4+ - O2- 형광의 시간 거동...................................84
4-6. Eu3+의 농도에 따른 Gd3+와 Eu3+형광의 수명시간 분석.............................................................................88
4-7. 고온에서 K2LnZr(PO4)3 (Ln = Y, Gd, Eu)의 방출 스펙트럼 분석......................................................................94
4-8. 온도에 따른 Zr4+ 방출 밴드의 수명시간 분석.............99
4-9. K2EuxGd1-xZr(PO4)3 (Ln = Gd, Y)의 CIE 분석........104
5. 결론......................................................................110
6. 참고문헌................................................................ 113
- Degree
- Doctor
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