Crystal, electronic structures and photoluminescence properties of rare-earth doped LiSi{sub 2}N{sub 3}
- Nitride Particle Group, Nano Ceramics Center, National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044 (Japan)
The crystal and electronic structures, and luminescence properties of Eu{sup 2+}, Ce{sup 3+} and Tb{sup 3+} activated LiSi{sub 2}N{sub 3} are reported. LiSi{sub 2}N{sub 3} is an insulator with an indirect band gap of about 5.0 eV (experimental value {approx}6.4 eV) and the Li 2s, 2p states are positioned on the top of the valence band close to the Fermi level and the bottom of the conduction band. The solubility of Eu{sup 2+} is significantly higher than Ce{sup 3+} and Tb{sup 3+} in LiSi{sub 2}N{sub 3} which may be strongly related to the valence difference between Li{sup +} and rare-earth ions. LiSi{sub 2}N{sub 3}:Eu{sup 2+} shows yellow emission at about 580 nm due to the 4f{sup 6}5d{sup 1}{yields}4f{sup 7} transition of Eu{sup 2+}. Double substitution is found to be the effective ways to improve the luminescence efficiency of LiSi{sub 2}N{sub 3}:Eu{sup 2+}, especially for the partial replacement of (LiSi){sup 5+} with (CaAl){sup 5+}, which gives red emission at 620 nm, showing highly promising applications in white LEDs. LiSi{sub 2}N{sub 3}:Ce{sup 3+} emits blue light at about 450 nm arising from the 5d{sup 1}{yields}4f{sup 1}5d{sup 0} transition of Ce{sup 3+} upon excitation at 320 nm. LiSi{sub 2}N{sub 3}:Tb{sup 3+} gives strong green line emission with a maximum peak at about 542 nm attributed to the {sup 5}D{sub 4}{yields}{sup 7}F{sub J} (J=3-6) transition of Tb{sup 3+}, which is caused by highly efficient energy transfer from the LiSi{sub 2}N{sub 3} host to the Tb{sup 3+} ions. - Graphical abstract: Local crystal structure and luminescence spectra of Li{sub 1-2x-y}Ca{sub y}Eu{sub x}Si{sub 2-y}Al{sub y}N{sub 3}. The emission band of Eu{sup 2+} shifts from yellow to red spectral region by the double substitution Ca{sup 2+}{yields}Li{sup +} and Al{sup 3+}{yields}Si{sup 4+} simultaneously in Li{sub 1-2x}Eu{sub x}Si{sub 2}N{sub 3} due to the significant changes in the local environment of the Li{sub Ca,Eu} ions.
- OSTI ID:
- 21212193
- Journal Information:
- Journal of Solid State Chemistry, Vol. 182, Issue 2; Other Information: DOI: 10.1016/j.jssc.2008.10.031; PII: S0022-4596(08)00560-4; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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