INORGANIC AND ORGANICALLY MODIFIED RARE-EARTH-DOPED SILICA-GELS

The fluorescence properties of inorganic and organically-modified rare -earth-doped sol-gel silica are presented. Eu3+-doped ornosils were pr epared from Si(OCH3)(4) and CH3Si(OCH3)(3), (CH3)(2)Si(OCH3)(2), (CH3) (2)Si(OC2H5)(2), or (n-C3H7)Si(OCH3)(3) in various proportions. Er3+-d oped ornosils were prepared using Si(OC2H5)(4) and CH3Si(OC2H5)(3), (C H3)(2)Si(OC2H5)(2), or C2H5Si(OC2H5)(3). Gels derived from Si(OCH3)(4) were also doped with the fluorinated Eu3+ precursors Eu(fod)(3), (CF3 SO3)(3)Eu, and (CF3CO2)(3)Eu.3H(2)O. The effect of metal ion codopants , which are known to inhibit clustering of Eu3+ in sol-gel silica, on Er3+ fluorescence is also considered. Fluorescence line-narrowing stud ies of Eu3+-doped samples indicated that significant Eu3+ clustering o ccurs in both the ornosils and fluorinated precursor compositions. Lif etime measurements of the Eu3+- and Er3+-doped ornosils showed longer lifetimes at low heat treatment temperatures relative to purely inorga nic sol-gel silica, but no significant difference remained in fully de nsified samples. The longest lifetimes were observed for samples doped with the fluorinated precursors, indicating that the fluorinated liga nds are effective at reducing the water content in densified gels.