期刊
JOURNAL OF MATERIALS CHEMISTRY
卷 22, 期 27, 页码 13723-13731出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c2jm31631e
关键词
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资金
- NSFC [11174005, 11074315, 90922022, 10804001]
- SRF for ROCS, SEM
- program for innovative research team in Anhui Normal University of China
- MEC-Spain [MAT2011-24586]
The electronic properties and the 4f -> 5d transitions of the dopant Ce3+ ions located at the two crystallographic lutetium sites of Lu2SiO5 (LSO) are investigated using the hybrid density functional theory (DFT) with the HSE06 functional and the wavefunction-based embedded cluster methods, respectively. The HSE06 calculations give a band gap of 6.35 eV for LSO, which agrees well with the reported experimental values between 6.4 and 6.8 eV. It is found that Ce3+ prefers strongly to occupy the seven-coordinated (Lu1) site over the six-coordinated (Lu2) one. The energy gaps between the occupied Ce3+ 4f band and the valence band maximum of the host are predicted to be 2.81 and 3.07 eV for Ce-Lu1 and Ce-Lu2 substitutions, respectively, which are close to the experimental data of 2.6-2.9 eV. Based on the wavefunction-based CASSCF/CASPT2 embedded cluster calculations for the energies of the Ce3+ 4f(1) and 5d(1) levels, the experimentally observed 4f -> 5d transition bands are identified in association with the two substitutions. The predicted transition energy and intensity patterns for Ce-Lu1 substitution are in fairly good agreement with those of the experimental absorption spectrum. The variations of the two lowest 4f -> 5d transition energies with the substitutions are finally discussed in terms of the changes of the centroid-energy difference and the crystal-field splitting with the local coordination geometries.
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