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Coordination environment evolution of Eu3+ during the dehydration and re-crystallization processes of Sm(1-x)Eu(x)[B9O13(OH)4]·H2O by photoluminescent characteristics.
- Source :
-
Dalton transactions (Cambridge, England : 2003) [Dalton Trans] 2013 Dec 14; Vol. 42 (46), pp. 16318-27. - Publication Year :
- 2013
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Abstract
- There are limited photoluminescence (PL) studies for rare earth borates with crystalline water molecules, which are usually supposed to have low PL efficiency because the vibrations of H2O or -OH may lead to emission quenching. We investigated the PL properties of Sm(1-x)Eu(x)[B9O13(OH)4]·H2O (x = 0-1.00) and their dehydrated products α-Sm(1-x)Eu(x)B5O9. There is no quenching effect in those studied polyborates because the large borate ionic groups isolate the Eu(3+) activators very well. Sm(3+) and Eu(3+) are basically separated luminescent activators. Comparatively, Sm(3+) shows a very small emission intensity, which can be almost ignored, therefore our interest is focused on the Eu(3+) luminescence. By TG-DSC and powder XRD experiments, we defined three weight-loss steps for Eu[B9O13(OH)4]·H2O and a re-crystallization process to α-EuB5O9, during which luminescent spectra of Eu(3+) are recorded. It shows an interesting variety and therefore is a good medium to understand the coordination environment evolution of Eu(3+), even for the intermediate amorphous phase. In fact, the coordination symmetry of Eu(3+) in the amorphous state is the lowest. The high efficiency of the f-f transitions and large R/O value (3.8) imply this amorphous phase is potentially a good red-emitting UV-LED phosphor. Anhydrous α-EuB5O9 shows the highest luminescent efficiency excited by Eu(3+) CT transition. In addition, α-Sm(1-x)Eu(x)B5O9 was synthesized by a sol-gel method directly for the first time, and α-EuB5O9 shows superior PL properties due to its better crystallinity. A lot of hydrated polyborates with crystalline water molecules remain unexplored and our study shows their potential as good phosphors.
Details
- Language :
- English
- ISSN :
- 1477-9234
- Volume :
- 42
- Issue :
- 46
- Database :
- MEDLINE
- Journal :
- Dalton transactions (Cambridge, England : 2003)
- Publication Type :
- Academic Journal
- Accession number :
- 24061473
- Full Text :
- https://doi.org/10.1039/c3dt51875b