期刊
JOURNAL OF MATERIALS CHEMISTRY C
卷 1, 期 47, 页码 7856-7865出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c3tc31628a
关键词
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资金
- European Union
- Freistaat Thuringen
- Leuchtstoffwerk Breitungen GmbH (Germany) [2008FE0070]
- Shanghai Institute of Ceramics [Y34ZC130G]
- Ministry-province jointly constructed cultivation base for state key laboratory of processing for non-ferrous metal and featured materials, Guangxi Zhuang Autonomous Region [12KF-11]
The electronic structure of SrAlSi4N7 was calculated using the CASTEP code and SrAlSi4N7 is an intermediate band gap semiconductor with an indirect energy gap of 3.6 eV. Ce3+ and Yb2+-activated SrAlSi4N7 samples were prepared by a solid-state reaction method at high temperature, and their photoluminescence properties were investigated. SrAlSi4N7:Ce3+ shows a broad band emission in the wavelength range of 450-700 nm, originating from the 5d(1)-4f(1) transition of Ce3+. The emission band of Ce3+ shifts to longer wavelength with an increase of Ce3+ concentration due to the increased Stokes shift and reabsorption by Ce3+. SrAlSi4N7:Yb2+ can be excited efficiently over a broad spectral range between 300 and 550 nm, and exhibits a single intense red emission at 600 nm with a full width at half maximum of 95 nm due to the electronic transitions from the excited state of 4f(13)5d to the ground state 4f(14) of Yb2+. The low energy of Yb2+ emission in SrAlSi4N7 can be attributed to the large nephelauxetic effect and crystal field splitting due to the coordination of Yb2+ by nitrogen. In addition, Sr1-2xCexLixAlSi4N7 shows higher thermal stability in air than that of Sr1-yYbyAlSi4N7 (0 <= x, y <= 0.1). A white-light LED can be generated by using single SrAlSi4N7:Ce3+ as the wavelength conversion phosphor combined with a blue LED chip (InGaN). The obtained LED exhibits a luminous efficiency of 74.3 lm W-1 at a corrected color temperature (CCT) up to 6350 K, and the color rendering index (CRI Ra) is around 78. These novel developed yellow-red phosphors have potential applications in spectral conversion materials for white-LEDs.
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