Xerogels, silica-containing

Scheme I. Syntheses of silica xerogel nanocomposites containing nanoclusters of Fe2P, C02P, or Ni2P.

Figure I. TEM micrographs of silica xerogel nanocomposites containing nanoclusters of Fe2P (A), C02P (B), or Ni2P (C - NiL 4 precursor D - NiL 2Cl2 precursor).

Figure 4. Magnetization versus temperature plots for a silica xerogel nanocomposite containing nanoclusters of Fe2P.

Figure 5. Magnetization versus applied field plots at 150 K, 200 K, 250 K, and 300 K for a silica xerogel nanocomposite containing nanoclusters of Fe2P.

Pinholes pose another threat. The effect of the presence of metals can be seen in Figure 7.14. Here silica based Xerogels were prepared with various amounts of metals. The near surface change in the 3-to-2 photon ratio was used to estimate the range of positronium. The same model as in the case for porous MSSQ was used. The range dropped from 1.55 0.05 mm in the plain silica sample to 0.15 0.07 mm in the case of tantalum and to 0.8 0.09 pm in the iron containing sample. 

Using of Fe-containing aqueous solutions for xerogels impregnation results in the preparation of hydroxylated silica gel-glass doped ferrum(III). The presintered... 

Colloidal support such as small Si02 particles restrict interparticle diffusion of silver atoms when formed by radiolysis of the ions at their surface. The silver oligomers absorbing at 290 and 330 nm are observed by pulse radiolysis. They are stable with respect to coalescence but they are oxidized by MV, O, Cu and RufNHj)/. Alumino-silica gels with silver ions give after irradiation optically clear xerogels containing silver clusters from 2.5 to 4.5 nm. 

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