In Situ Dehydroxylation in Eu3+-Doped Sol−Gel Silica

Fluorescence line narrowing and lifetime measurements are used to characterize the extents of clustering and hydroxyl quenching, respectively, in Eu 3+ -doped sol−gel silica glasses prepared using europium trifluoromethanesulfonate (triflate). A triflate ((CF 3 SO 3 ) 3 Eu) rather than a traditional nitrate (Eu(NO 3 ) 3 ·6H 2 O) precursor is used as the rare earth ion dopant in order to determine the feasibility of effecting chemical dehydroxylation via in situ fluorination by incorporating fluorine directly as a ligand substituent of the Eu 3+ precursor. In samples doped only with Eu 3+, the use of the triflate precursor leads to no noticeable differences in hydroxyl quenching of Eu 3+ fluorescence or Eu 3+ aggregation relative to samples prepared with a nitrate precursor. Beneficial effects are observed, however, in samples codoped with Al 3+ or Sr 2+ . When Al 3+ or Sr 2+ is included in the synthesis, a reduction in hydroxyl quenching of Eu 3+ is observed when the triflate precursor is used relative to the nitrate precursor. In addition, (CF 3 SO 3 ) 3 Al is found to be as effective at inhibiting Eu 3+ clustering as the previously reported Al(NO 3 ) 3 ·9H 2 O and (C 4 H 9 O) 2 Al−O−Si(OC 2 H 5 ) 3 precursors. The effect of incoporating fluorine via FSi(OC 2 H 5 ) 3 is also briefly considered and gives mixed results which differ for nitrate and triflate Eu 3+ precursors.