title: Europium-doped mesoporous titania thin films: rare-earth locations and emission fluctuations under illumination.
abstract: Herein, Eu(III)-doped 3D mesoscopically ordered arrays of mesoporous and nanocrystalline titania are prepared and studied. The rare-earth-doped titania thin films-synthesized via evaporation-induced self-assembly (EISA)-are characterized by using environmental ellipsoporosimetry, electronic microscopy (i.e. high-resolution scanning electron microscopy, HR-SEM, and transmission electron microscopy, HR-TEM), X-ray diffraction, and luminescence spectroscopy. Structural characterizations show that high europium-ion loadings can be incorporated into the titanium-dioxide walls without destroying the mesoporous arrangement. The luminescence properties of Eu(III) are investigated by using steady-state and time-resolved spectroscopy via excitation of the Eu(III) ions through the titania host. Using Eu(III) luminescence as a probe, the europium-ion sites can be addressed with at least two different environments within the mesoporous framework, namely, a nanocrystalline environment and a glasslike one. Emission fluctuations ((5)D(0)-->(7)F(2)) are observed upon continuous UV excitation in the host matrix. These fluctuations are attributed to charge trapping and appear to be strongly dependent on the amount of europium and the level of crystallinity.
authors.affiliation: CNRS, Université de Bordeaux, ICMCB, 87 avenue du Dr. A. Schweitzer, 33608 Pessac, France. leroy@icmcb-bordeaux.cnrs.fr
authors.forename: Celine Marie
authors.initials: CM
authors.lastname: Leroy
authors.forename: Thierry
authors.initials: T
authors.lastname: Cardinal
authors.forename: Veronique
authors.initials: V
authors.lastname: Jubera
authors.forename: Mona
authors.initials: M
authors.lastname: Treguer-Delapierre
authors.forename: Jerome
authors.initials: J
authors.lastname: Majimel
authors.forename: Jean Pierre
authors.initials: JP
authors.lastname: Manaud
authors.forename: Renal
authors.initials: R
authors.lastname: Backov
authors.forename: Cedric
authors.initials: C
authors.lastname: Boissière
authors.forename: David
authors.initials: D
authors.lastname: Grosso
authors.forename: Clement
authors.initials: C
authors.lastname: Sanchez
authors.forename: Bruno
authors.initials: B
authors.lastname: Viana
authors.forename: Fabienne
authors.initials: F
authors.lastname: Pellé