Liquid precursor solutions

Flame spray pyrolysis (FSP) a liquid precursor solution is sprayed into the flame and ignites its combustion drives the flame process. 

The effects of each of these process parameters will subsequently be discussed as it apphes to the CCVD process that employs liquid precursor solutions. (Some of these results are applicable also to vapor-source CCVD). 

Several other approaches to thin-film deposition into porons materials from the liquid phase have been attempted, most notably the deposition of CnlnSe2 and CuInS2 from colloidal solutions by Czekelius et al. (1999), and of InP by Zaban et al. (1998). Spray pyrolysis of CuInS2 from liquid precursor solutions onto strnctnred substrates has been explored by Krunks et al. (1999, 2001). 

Photopolymerizable systems have received a lot of recent attention in biomaterial applications due to the ability to rapidly form a solid polymer (gel) from a liquid precursor solution (monomer or macromer) with spatial and temporal control under physiological conditions. The development of cytocompatible systems has provided the ability to form materials in the presence of proteins, cells, and tissues to allow for minimally invasive biomaterial-based therapies. In particular, photopolymerizable systems have been used extensively as dental restoratives, controlled microenvironments to study cellular behavior and develop tissue substitutes, and to encapsulate growth fartors and cytokines in a polymer matrix for controlled release applications. 

At the current time, liquid precursor (solution/sol/slurry) coating techniques have been the most successful for the deposition of oxides, such as monazite (LaP04) and porous oxides (carbon-oxide mixtures) onto oxide fiber tows [178, 179, 191, 192]. Atypical fiber coater is shown in Figure 10a [193]. In the coating process, a lighter, immiscible liquid is floated on the surface of the coating precursor. The immiscible liquid is used to remove excess sol from the coated tow and it allows for the coating of individual filaments with... 

Hybrid mixtures are used, in which one reactant is in particulate form while the other reactant is either a liquid or is dissolved to form a liquid precursor solution. 

Sol-gel is relatively simple to transfer to an industrial scale and is particularly suitable for the deposition of thin films, as it is based on the deposition of a thin layer of the liquid precursor solution over a substrate at room temperature (by dip coating, spin coating, and spraying techniques), followed... 

The liquid precursor solution was atomised at a constant pressure of 2x10 Pa and injected into the carrier gas flow before entering the plasma zone. The carrier gas composition, which was set by mass flow controllers, was a N2/O2 (97 3, vol.%) mixture with a total gas flow of 20 standard litres per minute. The gas mixture containing the precursor aerosol was injected into the plasma through a slit between the two top electrodes. The experiments were carried out at atmospheric pressure and ambient temperature. 

A number of new approaches to the way in which precursors are delivered to a substrate have been developed in which the precursor is dispersed into the gas phase without having to be volatile. These new systems each have their own advantages for a particular precursor depending on its physical state. Most of the delivery systems in use can be classified as one of the following a liquid injection system (LIS), where a precursor is vaporized directly from a neat liquid or solution containing the precursors a solid delivery system (SDS), where the precursor is vaporized... 

Figure 5.15. Gas chromatograms of liquid precursors for producing n-type Si films, namely, solution of CPS with white phosphorus dissolved at 1 wt% initial (nonirradiated) solution 20-min-, 25-min-, and 30-min-irradiated solutions and white phosphorus alone solution, for comparison, all of which were diluted with toluene before analysis. Trans-decalin was used as a standard for a quantitative estimation of an unreacted CPS monomer. [Reproduced with permission from Ref. 25. Copyright 2007 The Japan Society of Applied Physics.]...

Both wet-ceramic techniques and direct-deposition techniques require preparation of the feedstock, which can consist of dry powders, suspensions of powders in liquid, or solution precursors for the desired phases, such as nitrates of the cations from which the oxides are formed. Section 6.1.3 presented some processing methods utilized to prepare the powder precursors for use in SOFC fabrication. The component fabrication methods are presented here. An overview of the major wet-ceramic and direct-deposition techniques utilized to deposit the thinner fuel cell components onto the thicker structural support layer are presented below. 

Figure 7.8 FTIR spectra of (a) GPTMS liquid control, (b) GPTMS gel and (c) GPTMS Al(OBu)3 (2 1) hybrid gel. The gel and hybrid gel samples were obtained by drying the precursor solutions at room temperature for 6 days. (Reproduced from ref. 5, with permission.)...

Method //was designed for a bonded microreactor. After the channel was sealed with a Pyrex top plate using the anodic bonding technique, the liquid precursor was infiltrated into the microreactor through the outlet of the reactor under slight pressure and withdrawn. A thin film of solution remained on the walls of the microchannel. 

Process through which a network is formed from solution by a progressive change of liquid precursor(s) into a sol, to a gel, and in most cases finally to a dry network. 

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