Doped silicate gels

Knobbe E.T., Dunn B., Fuqua P.D., Nishida F. Laser behavior and photostability characteristics of organic dye doped silicate gel materials. Appl. Optics 1990 29 2729-2733... 

Young s modulus of bulk glass gel, 139 yttria-doped zirconia gel, 150 yttrium aluminum garnet. See YAG yttrium silicate, 151... 

Nogami M., Abe Y., Hirao K., Cho D.H. Room temperature pasistent spectra hole burning in Sm -doped silicate glasses prepared by the sol-gel process. Appl. Phys. Lett. 1995 66 2952-2954... 

Impregnated and doped sol-gel hybrids sometimes result in permanent immobilization of the guest molecule with zero observed leaching of the organics. However, because no covalent bonding is involved, some or even the entire organic modifier is removed from the silicate in most cases, particularly when an appropriate solvent is used for extraction. 

Along with these recent technologies, sol-gel entrapped catalysts made of organically modified silicates (ORMOSIL) doped with one or... 

Figure 6.5 A fluorinated organically modified silicate doped with [Ru(dpp)3]2+ is a highly sensitive 02 sensor. Fluorine here ensures unprecedented sensitivity and a remarkable stability (2% drift over 6 months). The material has been implemented in sol-gel handheld oxygen sensors that are already commercialized. (Reproduced from ref. 6, with permission.)...

In this chapter, recent progress in several key areas is reviewed. These areas are catagorized by material classification rather than by end-use application (1) bulk silica optics (2) optically active doped silica glasses (3) gel-polymer composites (4) organically modified silicates (ormosils) and (5) gradient-index glasses. These represent the five most significant developments in the area of bulk optical materials by the sol-gel process to date. 

Two-catalyst procedures have also been developed, which use both acid and base catalysis. For example, Schumann et al. (77) used a two-stage procedure to speed up entrapment of air-sensitive rhodium complexes. The procedure involved acid hydrolysis to form an initial sol, which was doped with metal complex, and base was added to induce condensation. The effect of this two-step procedure on gel structure was not examined The rhodium complex was effectively trapped within the silicate matrix, however, and was an active catalyst for hydrogenation of styrene and nitrobenzene. 

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