Doping sol-gel films

Javaid M., Keay P., A generic technique for coating doped sol-gel films onto the inside of tubes for use as colorimetric sensors,/. Sol-Gel Sci. Technol. 2000 17 55-59. 

Blue R., Stewart G., Fibre-optic evanescent wave ph sensing with dye doped sol-gel films, Intern. J. Optoelectron. 1995 10 211-222. 

M. Ahmad, N. Mohammad and J. Abdullah, Sensing material for oxygen gas prepared by doping sol-gel film with tris(2,2 -bipyridyl)dichlororuthe-nium complex, J. Non-Crystal. Solids, 290(1) (2001) 86-91. 

An additional experiment was performed for the two films that stayed intact during the experiments described in the previous paragraph in order to provide evidence of the self-healing effect of nanoreservoirs added to the coating. The nondoped and the nanocontainer-doped sol-gel films were removed from the NaCl bath after the above indicated storage period, defects were made artificially into the films in order to... 

Cu-mordenite in silica sol-gel films. The fabrication procedure of Cu-mordenite-doped sol-gel films was modified as compared with the above Cu-doped ones by the change of copper nitrate onto Cu-modrenite. The subsequent deposition of the sol onto quartz substrate resulted in formation of thin films similar to simple Cu-doped ones. Amount of Cu-mordenite was adjusted for fabrication of the films with sufficient optical quality. The films were heated in air at 500 C followed by heating in hydrogen atmosphere at 150-450 C. The latter temperature variance determined different reduction of Cu-mordenite, and similarly different results were obtained with mordenite within the silica sol-gel matrix. 

A PS PtOEP film was drop cast on the second, third, fourth, and fifth pairs when viewed in color, these pairs are orange due to the superposition of the green Alqg OLED EL and the red PtOEP PL. A GOx-doped sol-gel film was deposited on the third pair, while AOx and LOx were contained each in a separate glass well, whose base was the PtOEP-doped PS film, above pairs 4 and 5, respectively. The measurement was performed using a PMT. 

Guodong Q., Minquan W., Mang W., Xianping F., Zhanglian H. Synthesis in situ of2,2 -dipyridyl-Tb (III) complexes in silica gel. J. Mater. Sci. Lett. 1997 16 322-323 Hao X., Fan X., Wang M. Luminescence behavior of Eu(TTFA)j doped sol-gel films. Thin Solid Films 1999 353 223-226... 

Oxygen concentration can be measured directly with an oxygen sensitive Clark electrode. The doped sol-gel film is deposited onto the Pt cathode and oxygen concentration is measured by amperometric titration at imposed potential. Oxygen depletion can then be used to quantify glucose concentration (Fig. 21-4) (Bergogne, 1999). 

Recent years have seen an increasing attention being devoted to rare-earth-doped glasses, both in bulk and thin-film format, for the development of integrated optical amplifiers. Several papers have been published, concerning the properties of Nd-, Er-, and ErAT)-doped sol-gel films (Bahtat, 1996 Strohhofer, 1998 Almeida, 1999 Gongalves, 2002 Wilhelm, 2003). The characterization of active films requires, in addition to the properties considered in the previous sections, the measurement of the spectroscopic properties and of the gain coefficient. Moreover, to explain the emission properties, it... 

Plaschke M, Czolk R, Ache HJ (1995) Huorimetric determination of mercury with a water-soluble porphyrin and porphyrin-doped sol-gel films. Anal Chim Acta 304 107-113 Lee S-K, Okura 1 (1997) Porphyrin-doped sol-gel glass as a probe for oxygen sensing. Anal Chim Acta 342 181-188... 

In this chapter, the characterization of sol-gel-derived films and planar waveguides by optical spectroscopy methods has been reviewed and discussed. FTIR, Raman, UV-Vis-NIR, and fluorescence spectroscopies were used to analyze the structures of sol-gel inorganic or hybrid optical films. NP sizes in films doped with noble metal NPs or quantum dots have also been reviewed. Optical loss and Z-scan measurements on sol-gel optical waveguides or NP-doped sol-gel films were also discussed. 

Suah F.B.M., Ahmad M., Taib M.N., Applications of artificial neural network on signal processing of optical fibre pH sensor based on bromophenol blue doped with sol-gel film, Sens. Actuat B 2003 90 182-188. 

B.C. Dave, H. Soyez, J.M. Miller, B. Dunn, J.S. Valentine, and J.I. Zink, Synthesis of protein-doped sol-gel SiC>2 thin films evidence for rotational mobility of encapsulated cytochrome c. Chem. Mater. 7, 1431-1434 (1995). 

The incorporation of Ru(II) chelates in various types of silica sol-gel-based composite films is another mode of immobilization.262,280-284 Silica sol-gel materials provide some advantages over organic polymers such as the ease with which they can be prepared, modified, and doped with various reagents. Particularly, silica sol-gel films are stable upon continuous electrochemical oxidation or upon drying the gels in a high humidity environment. 

Other properties which have contributed to the attractiveness and versatility of the sol-gel doping approach are the chemical, photochemical and electrochemical inertness as well as the thermal stability of the matrix the ability to induce electrical conductivity16 the richness of ways to modify chemically the matrix and its surface as well as the above-mentioned controllability of matrix structural properties the enhanced stability of the entrapped molecule1,17 the ability of employing the chromatographic properties of the matrix for enhanced selectivity and sensitivity of reactions with the dopant4 the simplicity of the entrapment procedure the ability to obtain the doped sol-gel material in any desired shape (powders, monoliths, films, fibers) and the ability to miniaturize it18,19. 

Similarly, CdS NCs capped with mercaptopro-pyltrimethoxysilane (MPTMS) were added to alcohohc solutions of TEOS or TMOS and subsequently incorporated into sihca matrices. Pb and Hg-based NCs have also been synthesized with MPTMS as the capping agent, and the role of the pendant siloxy groups is again to anchor the NCs to the sihca, silica-titania, or zirconia networks. Zirconia films doped with PbS NCs were prepared with refractive indices up to 1.53 and a third-order susceptibility value of 1.3 X 10 esu. Higher refractive index sihca-titania sol gel films doped with PbS (n = 1.63) were also fabricated. ... 

Our recent investigations demonstrated that sol-gel films doped with lanthanides allows strong enhancement of photoluminescence (PL) when fabricated in porous anodic alumina (PAA) [6]. In the present paper, we report on investigations of Eu- and Tb-doped In203 and Sn02 sol-gel-derived films fabricated in PAA in view of an application in EL devices. 

Fabrication of doped sol-gel silica films. Precursor solutions for sols were prepared by mixing tetraethoxysilane, ethanol and water with HCl as catalyst in the molar ratio 1 6 6 0.08, respectively. That is conventional procedure commonly used for silica sol-gel films preparation [4]. Cu-doped films were fabricated f romthe sols mixed with different amount (5-30 wt.%) of Cu(N03)2 by means of spincoating on a quartz substrate under the rotation speed 2000 rev/min. Films were heated at 500°C during 1 min in air. These films contain copper in the form of CuO that was established by the direct XRD analysis [5]. A heat treatment of the Cu-doped silica films in hydrogen atmosphere at 600 C for 1 h resulted in reduction of copper oxide to the finely dispersed metallic copper. 

Figure 1. (a) Absorption (DRS) spectra of Cu-mordenites reduced under 250°C with different MR and (b) usual absorption spectra of the Cu-doped silica sol-gel films, of these films with Cu-mordenite with MR = 206 and the corresponding Cu-mordenite reduced under 450°C. 

The two methods for synthesis of copper nanoparticles in dielectric matrices by the hydrogen reduction of copper ions are shown within the Cu-doped silica sol-gel films and the hybrid Cu-zeolite-silica sol-gel optical materials on transparent substrate. Presence of zeolite microcrystals witin sol-gel films gives more flexibility in variation of copper nanoparticle preparation. Optical features of copper nanoparticles in these systems are determined by their size and properties of surrounding medium and presented as the plasmon resonance band with different line profile. 

As described in Sect. 3.2.3, the GOx could be successfully doped in a sol-gel film that is spin-coated above the PtOEPiPS film, and its activity was stable, i.e., it did not degrade appreciably over time. In contrast, while LOx and AOx could also be embedded in a sol-gel film, reduced enzyme activity within a few measurements limited their usefulness. The sensing elements for lactate and alcohol therefore consisted of the respective enzymes dissolved in a buffer solution to which the analytes were added. In this geometry, the container with the reaction mixture was t3rpically sealed from air. This approach was adopted due to the more complex responses observed in a cell open to air, where the DO was constantly replenished. 

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