Spray-pyrolysis method

Spray-pyrolysis method is a useful method for the synthesis of high purity, narrow size distribution, homogeneous cranposition of oxide particles with spherical morphology. 

Flowmeter Ultrasonic nebulizer Peristatic pump Solution Water bath Immersion cooler 

Fig 12.4 Schematic diagram of the experimental apparatus for ultrasonic spray pyrolysis synthesis. Reproduced with permission from [45]. Copyright 2002 Elsevier 

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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. 

Hsu CS and Hwang BH. Microstructure and properties of the La06Sr04Co02Fe08O3 cathodes prepared by electrostatic-assisted ultrasonic spray pyrolysis method. J. Electrochem. Soc. 2006 153 A1478-A1483. 

La0 2Sro8Feo55Tio 4503 8 (LSFTO) powder, synthesized by using the spray pyrolysis method, was obtained from Praxair Specialty Ceramics (Woodinville, WA). The powder was preheated at 1250°C for 10 h in air with a 3°C/min ramp rate. The preheated powder was ground with ethanol in a mortar for more than 30 min. After drying to remove the ethanol, the powder was pressed into a cylindrical shape at 5000 psi with a 1 in. diam die. Dense ceramic disks were obtained by sintering in air at 1300°C for 20 h and 1400°C for 10 h. The sintered disks had a density of 90.3% of the theoretical den-... 

Fig. 18.14 Ti02 film deposited by spray-pyrolysis method using TiCF/titanium isopropoxide as the precursor [reprinted from Okuya et al. (1999), copyright 1999, with permission from Elsevier]...

Dican, S., Caglar, Y., Caglar, M. and Yakuphanoglu, F. (2006). Electrical conductivity, optical and structural properties of indium-doped ZnO nanofiber thin film deposited by spray pyrolysis method. Phys. E35(l), 131-138. 

Z.Y. Li, H. Maeda, K. Kusakabe, S. Morooka, H. Anzai and S. Akiyama, Preparation of palladium-silver alloy membranes for hydrogen separation by the spray pyrolysis method. J. Membr. Sci., 78 (1993) 247. 

Figure 1 is the current-potential relationship measured in an aqueous solution containing 0.1 M pyrrole and 0.1 M Na2SO using a polycrystalline Ti02 thin layer electrode prepared by spray pyrolysis method (25). 

Co-precipitation method, sol-gel method, freeze drying method, spray pyrolysis method and combustion method are usually used to prepare powders. Powders prepared by the combustion method have small size, high purity and good chemical stability. Urea, glycine, carbohydrazide, citric acid and so on were used as the fiiel in this paper. According to the previous report, Gd203 powders have a monoclinic structure when citric acid was used as the fiiel. While we used the citric acid and EDTA as combination fuel, the Gd203 powders prepared had the cubic structure in this paper. As comparison, oxalic acid co-precipitation was also used to prepare the powders. 

Although the spray pyrolysis method is has been successfully used to prepare a variety of powdered materials, it is difficult to efficiently produce considerably fine separable particles in nanometer scale due to the formation of a three-dimensional network. The salt-assisted spray pyrolysis method has been proposed for separating these nanoparticles by introducing some compounds that can distribute on the surface of the particles to prevent agglomeration [88, 89],... 

Figure 6-11. Ce02 nanoparticles synthesized by the salt-assisted spray pyrolysis method at 1073 K (Reproduced with permission from ref. 89. Copyright 2003 The Royal Society of Chemistry. )...

A variant of the spray pyrolysis method based on electrostatic spray-assisted vapor deposition (ESAVD) can also be used [110] in which the mixed co-solvent and precursor electrolyte is atomized by an electric field. The morphology of the thin films obtained from this method is very dependent on the process temperature (Figure 5.14) [110]. For example, in the case of CdS deposition [110] amorphous films are obtained below 300°C (process I in Figure 5.14). Cadmium... 

Joni, I.M., Purwato, A., Iskandar, F., Hazata, M., and Okuyama, K., Intense UV-light absorption of ZnO nanoparticles prepared using a pulse combustion-spray pyrolysis method. Chemical Engineering Journal, 2009, 155,433-441. 

By the spray pyrolysis method, prepared nanoparticles can be controlled under 100 nm. The reaction takes place in a nitrogen atmosphere followed by centrifugation and calcination process at high temperature to achieve the desired nanoparticles. It was one a time-consuming and cost-effective technique for the synthesis of nanoparticles and also it leads to some toxicity to the environment by using toxic organic substances (Ghorbani et al., 2011). 

Fig. 37.1 Basic steps of spray pyrolysis method for zirconium hydroxychloride (ZrO(OH)Cl). Once the (ZrO(OH)Cl) powders are relatively dried, they decompose to Zr02 and HCl gas. Zr02 powders remain in the collector and HCl gas goes to the carrier gas. (Reproduced from [1] with permission. Copyright 2006 Institute of Physics)...

W.-N. Wang, I. W. Lenggoro, Y. Terashi, Y. C. Wang, K. Okuyama Direct synthesis of barium titanate nanoparticies via a low pressure spray pyrolysis method, J. Mater. Res. 20 (10), 2873-2882 (2005b). 

Y. Itoh, M. Abdullah, K. Okuyama Direct preparation of nonagglomerated indium tin oxide nanoparticles using various spray pyrolysis methods, J. Mater. Res. 19 (4), 1077-1086 (2004). 

Takatori and his collaborators in Toyota Research Center were one of the first who developed and systematically studied the emulsion combustion method (ECM) [3]. This method is basically a combination of the microemulsion wet chemistry and the flame spray pyrolysis methods. In ECM, an aqueous solution of a metal salt is mixed with a fuel such as kerosene and a small amount of an emulsifier or surfactant to obtain a water-in-oil (W/O) type of emulsion. Using a spray nozzle, the solution is then atomized to produce a spray. The size of the mother emulsion droplets depends on the atomizer type and the atomization conditimis, and is on the order of 10 pm for air-assist nozzles. The size of the dispersed micro-solution droplets depends on the string process and surfactant, and is about 1 pm [3]. Figure 40.1 shows a schematic diagram of the ECM. 

Nano-sized MgO particles with weU-crystaUized structures have been prepared by using spray pyrolysis method with solutions of citric acid [219]. The optimum concentration of citric acid was 0.4 M, in order to obtain micrometer-sized MgO particles. The function of citric acid in the spray solution was to alter the thermal properties of the solution and thus to control the morphologies of the particles. The micrometer-sized precursor particles with hollow porous structures which were... 

A series of works have been reported on preparation of YAG based phosphor powders by using spray pyrolysis method, with spray solutions of different fluxes [226-229]. It has been demonstrated that spray pyrolysis method can be used to control the morphologies and sizes of the YAG based phosphor powders in a very feasible way. Highly spherical particles with well controlled size distribution can be readily synthesized by optimizing the processing parameters. 

Compared to the other deposition techniques, the spray pyrolysis method shows quite low separation factor, indicating that the technique needs some improvements, especially for producing dense films. 

Yoshino, K., Fukushima, T.,and Yoneta, M. Structural, optical and electrical characterization on ZnO fihn grown by a spray pyrolysis method. Journal of Material Science Materials in Electronics, 16(7), 403 08 (2005). 

The concept or the basis of spray pyrolysis method assumes that one droplet forms one product particle. To date, submicrometer- to micrometer-sized particles are typically formed in a spray pyrolysis process. A variety of atomization techniques have been used ftn- solution aerosol formation, such as ultrasonic spray pyrolysis, electrospray pyrolysis, low pressure spray pyrolysis using a filter expansion aerosol generator (FEAG), salt-assisted spray pyrolysis, two-fluid pyrolysis method, etc. [15-18]. These atomization methods differ in droplet size, rate of atomization, and... 

Finally, the ultrasonic atomization is shown as a very effective method for generating small droplets. The droplets produced by ultrasonic atomizer are 2-4 p,m, but atomization rate is limited to <2 cm /min. Ultrasonic spray pyrolysis method is the most convenient method to obtain spherically shaped fine particles. The droplets are formed from feeding solution by means of an ultrasonic oscillator with frequency in the order of several megahertz or shghtly less than 1 MHz [15,27]. 

Janadkovid, Dj., Kostic-Gvozdenovic, Lj., Cirjakovic, R., Jokanovic, V., Petrovic-IAelevic, J., and Uskokovic, D., Synthesis of spinel powders by the spray pyrolysis method. Key Eng. Mater., 132-136, 213-216, 1997. 

Template-Assisted Ultrasonic Spray Pyrolysis Method 98... 

Park SH, Yoon CS, Kang SG, Kim H-S, Moon S-L Sun Y-K (2004) Synthesis and structural characterization of layered Li[Nii/3Coi/3Mni/3]02 cathode materials by ultrasonic spray pyrolysis method. Electrochim Acta 49 557... 

In-situ formation of CNTs in alumina matrices produced by spray pyrolysis might be considered an alternative to the CVD method, which involves spraying a slurry of ferrocene (metal catalysts) and alumina nanoparticles in xylene (hydrocarbon source) at 1000"C under Ar atmosphere [31]. However, the technique produced flake-like mixtures, which showed heterogeneous distribution of CNTs in the matrix material in through-thickness direction. The same spray pyrolysis method was used to fabricate C-SiC-carbon nanotube composite flakes [32]. Other ceramic materials including SiC [33], TiN [34], Fe2N [34], and BaTiOs [35] have also been demonstrated as matrices for incorporation of CNTs by the CVD method. 

The diffraction patterns of the decomposed aerosol products of TiO and Fe-TiOj obtained by spray pyrolysis showed poor crystallinity. Specimens were therefore further calcined at temperatures of 823K, 873IG 973K and 1073K in air for a period of 2 hours in order to improve their crystalline structure. Fig.1. shows the x-ray diffraction patterns of titanium dioxide (anatase), and a series of iron-titanium oxide specimens of nominal Fe(IlI) concentration equivalent to 0.1, 1, 2, 5 and 10 atom%, prepared by the spray pyrolysis method and subsequently calcined at 823K in air for 2 hours. 

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