Indigenous Spray Pyrolysis Techniques Basics and working of spray pyrolysis technique

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Indigenous Spray Pyrolysis Techniques 
 
Basics and working of spray pyrolysis technique 
Spray pyrolysis (Fig. 2.1) is a powerful technique among various technique mention 
above to synthesize a wide variety of high purity, chemically homogeneous thin films. Large 
quantities of oxide powders with homogeneous particle sizes and crystalline sizes less than 
100 nanometers may be produced by this method. The method involves spraying a solution 
usually in aqueous, containing soluble of the constituent atoms of the desired compound on to 
a heated substrate. Every sprayed droplet reaching the substrate undergoes pyrolysis 
decomposition and forms a single crystallite or a cluster of crystallites of the products.
Different parameter like volume of solution sprayed substrate temperature, solution and 
flow rates concentration of the solution distance between the substrate and the spray nozzle
have to be optimized to get a homogeneous uniform thickness and good quality of the film. 
Hydrolysis and pyrolysis are the main chemical reactions involved in this process. SP is a 
convenient, simple and low-cost method for the deposition of large-area thin films, and it has 
Fig.: Spray Pyrolysis System 

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been used for a long time. Additionally it is a low cost method the composition and 
microstructure can easily be controlled and the deposition takes place at moderate 
temperatures of 100 ºC - 500 ºC. Furthermore it offers the possibility of mass production 
which is suitable for industrial applications. The apparatus, needed to carry out the chemical 
spray process, consists of an atomizer the spray solution and a substrate heater. The spray 
deposition has been used to prepare coatings for the cover glass, required for flat plate 
collectors and cutter tubes used in the focusing type cylindrical collectors. However, as every 
other method, SP has some disadvantages such as the possibility of oxidation of sulfides 
when processed in air atmosphere, difficulties regarding the growth temperature 
determination.