Spray pyrolysis

As per the literature, there are two types of approach vapour feed-flame spray pyrolysis and liquid feed-flame spray pyrolysis (LF-FSP). However, it is often difficult in the vapour feed process to 

During spray-pyrolysis deposition, a precursor solution of metal salt and solvent is sprayed as fine droplets onto a heated substrate. When the droplets reach the heated substrate, they spread out and undergo pyrolytic decomposition. Water evaporates from the droplets and the precursor is converted to an oxide with the formation of solid particles.  

During the last century concerns over the availability of energy sources and the impact of combustion processes on the global environment have attracted more and more attention. The imperative reasons for the use of catalysts in combustion may be either to generate energy in catalytic heaters, boilers and gas turbine engines, or 

The technique itself consists of a precursor solution that is sprayed through an air atomizer on a heated substrate, producing thin films. It is well established that the morphology and quality of the deposited films are strongly linked to the snb-strate temperature. Defects, such as non-uniformity of the film, cracks and pores, are among the most frequent problems presented in the films deposited by spray pyrolysis [1]. 

For the technological use of the films obtained by spray pyrolysis it is necessary that some of its interesting features are understood and controlled. The relationship between the procedural parameters, the characteristics of the deposit microslnictures and the final properties obtained, is the foundation for understanding and mastering this technique. 

Kopp Alves et al.. Novel Synthesis and Characterization ofNanostructured Materials, Engineering Materials, DOl 10.1007/978-3-642-41275-2 3, 

In this process, porous particles are easily formed. The porosity is controlled by changing the precursor concentration in the droplets or by adjusting temperature profile in the furnace. Hollow particles can also be prepared when the solute concentration gradient is created during evaporation of solvent. Easy scaling up is a major advantage of this method, too. 

Instead of an electronic furnace, an r.f. inductively coupled plasma (ICP) is also used to generate high temperatures. This method is named a spray-ICP technique and has been applied for a wide variety of oxides. Another variation of the spray pyrolysis is the spray- drying method that uses slurry or sol of metal 

The impregnation method is convenient to disperse a small amount of well-fine particles on the surface of the support. An amount of supported particles depends on the concentration of the solution and pore volume of the support. Incipient wetness impregnation method is also used for precious control of the amount of the deposition. After evacuation of the support, the solution corresponded to the pore volume is added little by little and the surface of the support uniformly get wet. 

Ceria powders that are doped various cations such as Ca, Mg, AP,  

and Si , have been prepared according to the wetness impregnation method to investigate their effects on thermal stability of ceria. These impregnation methods are, of course, useful to synthesize ceria-based oxides supported on another oxides such as silica and alumina. The most advantage of the method is that highly dispersion is obtained. 

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Spray drying Spray lay-up Spray painting Spray pyrolysis Spray recrystallization Sprays... 

Another growing apphcation that overlaps the electrically functional area is the use of transparent conductive coatings or tin oxide, indium—tin oxide, and similar materials in photovoltaic solar ceUs and various optic electronic apphcations (see Photovoltaic cells). These coatings are deposited by PVD techniques as weU as by spray pyrolysis, which is a CVD process. 

Spray Pyrolysis. In spray pyrolysis, a chemical solution is sprayed on a hot surface where it is pyrolyzed (decomposed) to give thin films of either elements or, more commonly, compounds (22). Eor example, to deposit CdS, a solution of CdCl plus NH2CSNH2 (thiourea) is sprayed on a hot surface. To deposit Iu202, InCl is dissolved in a solvent and sprayed on a hot surface in air. Materials that can be deposited by spray pyrolysis include electrically conductive tin—oxide and indium/tin oxide (ITO), CdS, Cu—InSe2, and CdSe. Spray pyrolysis is an inexpensive deposition process and can be used on large-area substrates. 

In spray pyrolysis, very fine droplets are sprayed onto a heated substrate. The limitations of this process are the same as for spin-on coating. The same is often the case for preparing solid electrolytes by chemical vapor deposition (CVD) processes, which in addition are more expensive, and the precursors are often very toxic. 

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

Flame-assisted spray pyrolysis (FASP) this is similar to FSP, but the flame is sustained by a fuel. 

Preparation of titania nanopartidei of anatase phase by using flame spray pyrolysis... 

Various methods are applied to the synthesis of titania particles including sol-gel method, hydrothermal method [2], citrate gel method, flame processing and spray pyrolysis [1]. To utilize titania as a photocatalyst, the formation of ultrafme anatase titania particles with large crystallite size and large surface area by various ways has been studied [4]. 

In this work, flame spray pyrolysis was applied to the synthesis of titania particles to control the crystal structure and crystallite size and compared with the particle prepared by the conventional spray pyrolysis... 

Fig. 1. XRD patterns of titania particles by conventional spray pyrolysis wife various preparation tempaatures.

Fig. 2. Average anatase crystallite sizes and fractions of rutile phase as a function of preparation temperature in conventional spray pyrolysis.

Fig. 3. XRD patterns of titaoia particles prqmied by flame spray pyrolysis with various flame tecD eratur. ...

Another distinguishing feature of titania prepared by flame spray pyrolysis is the draar e of anatase crystallite size with the increase of flame temperature. Generally, the increase of preparation temperature increases the crystallite size in other processes such as sol-gel method, hydrothermal method [2, 3], flame processing and conventional spray pyrolysis. The decrease of crystallite size was directly related to the decrease of particle size. Fig. 5 shows SEM and TEM images of titania particles prepared by flame spray pyrolysis. 

Fig. 6. Comparison of initial rate with titama particles prepared by flame spray pyrolysis and spray pyrolysis.

Fig. 6 also shows the striking differeraa in photoactivties of the particles prqjared by conventional spray pyrolysis and flame ray pyrolysis. As the preparation tranperature was increased, the rate of TCE decomposition in liquid phase was decrease in the conventional spray pyrolysis whareas the reaction rate kept increasing with the increase of flame temperature. 

Compared with the conventional spray pyrolysis, flame spray pyrolysis produces titania particles that are strikingly different in crystd phase and surfece arra. The fraction of anatase phase increases with the increase of flame tempCTature while it decreases with the increase of preparation temperature in the conventional spray pyrolysis. The sur e area and... 

Iron sulfide as pyrite (FeS2) has been shown to be a promising photoactive material for photoelectrochemical and photovoltaic solar cells. Whereas a variety of methods have been employed for the preparation of thin films of this material, including CVT, MOCVD, spray-pyrolysis, and sulfidation of either iron oxide or iron, the direct efectrodeposition of FeS2 thin films has proven to be problematic. 

Silver(I) /3-diketonate derivatives have received significant attention due to the ease with which they can be converted to the elemental metal by thermal decomposition techniques such as metal organic chemical vapor deposition (MOCVD).59 The larger cationic radius of silver(I) with respect to copper(I) has caused problems in achieving both good volatility and adequate stability of silver(I) complexes for the use in CVD apparatus. These problems have been overcome with the new techniques such as super critical fluid transport CVD (SFTCVD), aerosol-assisted CVD (AACVD), and spray pyrolysis, where the requirements for volatile precursors are less stringent. 

Thermal treatment synthesis technique of mists formed from ultrasonic atomizer (Ultrasonic spray pyrolysis technique) Y203-Zr02, NiO, ZnS, BaTi03-SrTi03, MoS2, BiV04 [11-14]... 

Skrabalak SE, Suslick KS (2005) Porous MoS2 synthesized by ultrasonic spray pyrolysis. J Am Chem Soc 127 9990-9991... 

Dunkel SS, Helmich RJ, Suslick KS (2009) BiV04 as a visible-light photocatalyst prepared by ultrasonic spray pyrolysis. J Phys Chem C 113 11980-11983... 

Films at NASA GRC were deposited using homemade spray or aerosol-assisted chemical vapor deposition (AACVD) reactors to exploit the lower deposition temperature enabled by the simpler decomposition chemistry for the SSPs.6 9 AACVD is a simple and inexpensive process that offers the advantage of a uniform, large-area deposition, just like metal organic CVD (MOCVD), while also offering the low-temperature solution reservoir typical of spray pyrolysis methods. 

Krunks, M. Mikli, V. Bijakina, O. Hebane, H. Mere, A. Varema, T. Mellikov, E. 2000. Composition and structure of CuInS2 films prepared by spray pyrolysis. Thin Solid Films 361-362 61-64. 

Odier, P. Supardi, Z. De-Barros, D. Vergnieres, L. Ramirez-Castellanos, J. Gonzales-Calbet, J. M. Vallet-Regi, M. Villard, C. Peroz, Ch. Weiss, F. 2004. Spray pyrolysis for high Tc superconductor films. Supercond. Sci. Technol. 17 1303-1310. 

Jokanovic, V. Janackovic, D. J. Spasic, R Uskokovic, D. 1999. Modeling of nanostructural design of ultrafine mullite powder particles obtained by ultrasonic spray pyrolysis. Nanostruct. Mater. 12 349-352. 

Jin, M. H.-C. Banger, K. K. Harris, J. D. Cowen, J. E. Hepp, A. F. 2002. Thin film CuInS2 prepared by spray pyrolysis with single-source precursors. Proceedings of the 29th IEEE Photovoltaic Specialists Conference. IEEE, Piscataway, NJ. pp. 672-675. 

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