Precursor Solution

Vapor decomposition (14,15) iavolves dryiag, decomposiag, and vaporising a spray of salt precursor solution ia a plasma, and subsequentiy nucleating and growing ceramic particles ia the vapor. Silicon carbide [12504-67-5] SiC, powder is produced by this method. 

Infiltration (67) provides a unique means of fabricating ceramic composites. A ceramic compact is partially sintered to produce a porous body that is subsequently infiltrated with a low viscosity ceramic precursor solution. Advanced ceramic matrix composites such as alumina dispersed in zirconia [1314-23-4] Zr02, can be fabricated using this technique. Complete infiltration produces a homogeneous composite partial infiltration produces a surface modified ceramic composite. 

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

As a starting material, TTBP (Titinium tetraisoproxide, Aldrich Chem. Co. ltd., 98%) was dissolved in distilled water by adding nitric acid. Total titanium ion concentration was fixed at 0.5M. The precursor solution was converted into droplets by ultrasonic nebulizer of 1.7MHz. These droplets were transported to the reaction region by carrier gas. 

For this micro reactor version, the microstructured platelets were treated by anodic oxidation to obtain a nano-porous layer and impregnated with precursor solutions in organic solvents to obtain a V205 P205 Ti02 catalyst. 

TBP and injected into a hot ( 350 °C) solution of TOPO (12 g). The injection of CdSe precursors into the hot solution ofTOPO resulted in spontaneous nucleation of CdSe nanocrystals and a decrease in temperature. Once the temperature was stabilized, an additional amount (0.4 mL) of the precursor solution was added for the growth of the nucleated nanocrystals. Here, Ostwald ripening was avoided by separating the nucleation and growth processes. All the reagents and the reaction were kept under an Ar atmosphere to avoid fire hazard and surface oxidation of the nanocrystals. 

The ACTIV-OX chlorine dioxide system evaluated in this trial overcomes many of the problems associated with chlorine dioxide for the small water user. A chlorine dioxide precursor solution and a dilute acid solution are mixed in a 1 1 ratio immediately prior to injection into the water to be treated. The dose rate of chlorine dioxide is controlled by water meter signal to two proportioning pumps. The mixing of the two chemicals immediately produces a chlorine dioxide solution which is diluted to the required strength by injection into the water to be treated (Fig 3). 

Figure 5 29Si NMR of a silicalite-1 precursor solution with a molar ratio of 25 TEOS 9 TPAOH 152 H20 a) experimental spectrum, b), c), and d) simulated spectra of large components, narrow lines and all components respectively.

Figure 2.4. (a) Typical Schlenk-line and (b) distillation/reflux apparatus used in sol-gel synthesis of film precursor solutions. [Reprinted from Ref. 71, with permission.]... 

Because of these precursor modification reactions, the process chemistry of chelate processes is as complex, or more so, than that involved in sol-gel processes.78 However, it is typical for chelate processes that some control of process chemistry is sacrificed in return for more expedient solution preparation. For example, the hour-long (or longer) reflux processes that have been historically used in 2-methoxyethanol based sol-gel processing of ferroelectric films are not used. Rather, the entire solution preparation procedure is generally completed within one hour, with only the initial phase of the procedure being carried out under dry box and inert atmosphere conditions. Once the chelation reaction(s) has occurred, the hydrolysis sensitivity of the precursor solution is reduced to the point where the remaining process chemistry may be carried out under ambient conditions.46... 

Kato, K. Zheng, C. Dey, S. K. Torii, Y. 1997. Chemistry of the alkoxy-derived precursor solutions for layer-structured perovskite thin films. Int. Ferro. 18(l-4) 225-235. 

Schneller,T. Waser, R. 2007. Chemical modifications of Pb(Zr0.3,Ti07)O3 precursor solutions and their influence on the morphological and electrical properties of the resulting thin films. J. Sol-Gel Sci Tech. 42 337-352. 

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