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| 1 | Electronic structure of the SrAl_2O_4:Eu^(2+) persistent luminescence material显示文摘The electronic structure of the strontium aluminate (SrAl2O4:Eu2+) materials was studied with a combined experimental and theoretical approach. The UV-VUV synchrotron radiation was applied in the experimental study while the electronic structure of the non-optimized and optimized crystal structure were investigated theoretically by using the density functional theory. The structure of the va- lence and conduction bands as well as the band gap energy of the material together with the position of the Eu2+ 4f7 8S7/2 ground state were calculated. The calculated band gap energy (6.4 eV) agreed well with the experimental value of 6.6 eV. The valence band consisted mainly of oxygen states whereas the bottom of the conduction band of strontium states. In agreement with the experimental results, the calculated 4f7 8S7/2 ground state of Eu2+ lies in the energy gap of the host. The position of the 4f7 ground state depended on the Coulomb repulsion strength. The position of the 4f7 ground state with respect to the valence and conduction bands was discussed using theoretical and experimental evidence available. | Jorma Hls Taneli Laamanen Mika Lastusaari Janne Niittykoski Pavel Novák | 2009 | Journal of Rare Earths2009，27，4： | 9 |
| 2 | Synchrotron radiation investigations of the Sr_2MgSi_2O_7:Eu^(2+),R^(3+) persistent luminescence materials显示文摘The electronic and defect energy level structure of polycrystalline Sr2MgSi2O7:Eu2+,R3+ persistent luminescence materials were studied with thermoluminescence and different synchrotron radiation spectroscopies (UV-VUV emission and excitation, X-ray absorption near-edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS)). Special attention was paid on the effect of the R3+ co-dopants on the persistent luminescence properties of the materials. Theoretical calculations using the density functional theory (DFT) were carried out simultaneously with the experimental work. The experimental band gap energy (Eg) value of ca. 7.1 eV agreed very well with the DFT value of 6.7 eV. The variation of the Eg value was attempted to relate with the trap structure as well as with the different properties of the R3+ co-dopants. The trap level energy distribution depended strongly on the R3+ co-dopant except for the shallowest trap energy above the room temperature remaining practically the same, however. The different processes in the mechanism of persistent luminescence from Sr2MgSi2O7:Eu2+,R3+ were assembled and their contributions discussed. | Tuomas Aitasalo Jukka Hassinen Jorma Hls Taneli Laamanen Mika Lastusaari Marja Malkamki Janne Niittykoski Pavel Novák | 2009 | Journal of Rare Earths2009，27，4： | 5 |
| 3 | Defect aggregates in the Sr_2MgSi_2O_7 persistent luminescence material显示文摘The crystal and electronic structure of the Eu2+ doped and defect containing Sr2MgSi2O7 persistent luminescence material were studied using the density functional theory(DFT) .The defects may act as energy storage or even luminescence quenching centres in these materials,however their role is very difficult to confirm experimentally.The probability of vacancy formation was studied using the total en-ergy of the defect containing host.Significant structural modifications in the environment of the isolated defects,especially the strontium va-cancy,as well as defect aggregates were found.The experimental band gap energy of Sr2MgSi2O7 was well reproduced by the calculations.The defect induced electron traps close to the host's conduction band were found to act as energy storage sites contributing to its efficient per-sistent luminescence.The interactions between the defects were found to modify both the Eu2+ 4f7 ground state energy as well as the trap structure.The effect of charge compensation induced by the rare earth co-doping on the defect structure and energy storage properties of the persistent luminescence materials was discussed. | Jorma Hls Taneli Laamanen Mika Lastusaari Pavel Novák | 2011 | Journal of Rare Earths2011，29，12： | 2 |
| 4 | Persistent luminescence of Eu2+ doped alkaline earth aluminates, MAl2O4∶Eu2+ 显示文摘 | Jorma Holsa Hogne Jungner Mika Lastusaari etal | 2001 | J Alloys and Compounds2001，，： | 1 |
| 5 | X-ray powder diffraction study of the stability of solid solutions inLaO(Cl1-x Brx) 显示文摘 | Holsa J Lastusaari M Valkonen J | 1997 | J Alloys and Compounds1997，，： | 1 |
| 6 | 显示文摘 | Holsa Antic-Fidancev E Lastusaari M | 2003 | Jour- nal of Solid State Chemistry2003，171，12： | 1 |
| 7 | Effect of Mg 2+ and Ti IV doping on the luminescence of Y 2 O 2 S:Eu 3+显示文摘 | Jorma H?ls? Taneli Laamanen Mika Lastusaari Marja Malkam?ki Janne Niittykoski Eugeniusz Zych | 2009 | Optical Materials2009，，12： | 1 |
| 8 | Persistent lumines- cence of Eu2+ doped alkaline earth aluminates, MA1204 : Eu2+ 显示文摘 | HOls/: J Jungner H Lastusaari M | 2001 | J Alloy Compd2001，323，324： | 1 |
| 9 | Effect of grain size and concentration of active ions on structural and optical behavior of Eu3+-doped Y3Al5O12 nanocrystallites显示文摘 | Hreniak D H(o)ls(a) J Lastusaari M Strek W | | 0，，： | 1 |
| 10 | Persistent luminescence of Eu2+doped alkaline earth aluminates,MAl2O4∶Eu2+显示文摘 | HOLSA J JENNER H LASTUSAARI M | 2001 | Journal of Alloys and Compounds2001，323，： | 1 |
| 11 | Persistent luminescence of Eu2+ doped alkaline earth aluminates,MAl2O4:Eu显示文摘 | Jorma Holsa Hogner Jungner Mika Lastusaari | 2001 | Journal of Alloys and Compounds2001，，3： | 1 |
| 12 | A few remarks on the simulation and use of crystal field energy level schemes of the rare earth ions 显示文摘 | HiSlsii J Lastusaari M Mary ko M | 2005 | Journal of Solid StateChemistry2005，178，： | 1 |
| 13 | Persistent luminescence of Eu2+ doped alkaline earth aluminates, MAl2O4: Eu2+显示文摘 | HOLSA Jorma JUNGNER Hogne LASTUSAARI Mika | 2001 | J Alloys Compd2001，，： | 1 |
| 14 | Optically stimulated luminescence of persistent luminescence materials 显示文摘 | Fabienne Pelle Tuomas Aitasalo Mika Lastusaari | 2006 | Journal of Luminescence2006，，： | 1 |
| 15 | Optically stimulated luminescence of persistent luminescence materials 显示文摘 | Fabienne Pelle Tuomas Aitasalo Mika Lastusaari et al | 2006 | Journal of Lumines- cence2006，，： | 1 |
| 16 | Effect of temperature on the luminescence processes of SrAl2O4:Eu^2+显示文摘 | Aitasalo T Jean - Claude K Lastusaari M L | 2004 | Radiat Meas2004，，38： | 1 |
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