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2004
Luminescence
D 6540
Photoluminescent Layered Lanthanide Silicates. — The mixed lanthanide silicates
K3 [L n11-x Ln2x Si 3O8(OH)2] (Ln1:Y, Tb; Ln2: Eu, Er, Tb, and Gd) are prepared analo44- 012 gously
to compounds (III). The structure of these solids was elucidated by powder XRD
and by single crystal XRD for (IIId) (orthorhombic, space group Pnma, Z = 4, 180 K).
The compounds are further characterized by TGA, SEM, 29Si MAS NMR, and photoluminescence spectroscopy. (IIIb) is a room-temperature infrared phosphor, while (IIIc)
and (IIId) are visible emitters with output efficiencies comparable to standards used in
commercial lamps. The structure of these materials allows the inclusion of a second (or
even a third) type of Ln3+ ion in the framework and, therefore, the fine-tuning of their
photoluminescent properties. For the mixed Tb3+ /Eu3+ materials, evidence is found of
the inclusion of Eu3+ ions in the interlayer space by replacing K+ ions, further allowing
the activation of Tb3+-to-Eu3+ energy transfer mechanisms. — (ANANIAS, D.;
KOSTOVA, M.; ALMEIDA PAZ, F. A.; FERREIRA, A.; CARLOS, L. D.;
KLINOWSKI, J.; ROCHA*, J.; J. Am. Chem. Soc. 126 (2004) 33, 10410-10417;
Dep. Chem., Univ. Aveiro, P-3810 Aveiro, Port.; Eng.) — Schramke
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