Indigenous Spray Pyrolysis Techniques Basics and working of spray pyrolysis technique

Essentials of spray pyrolysis technique
 
Fig. 2.2 shows the schematic diagram of the spray pyrolysis technique. It mainly 
consists of preparation mask, air compressor, heater, spray nozzle, hot plate, gas regulator 
value and airtight fume chamber. 
 
Preparation of Mask 
In order to study the various properties of thin film, it is necessary that they must be 
properly patterned. The most commonly used method of patterning thin film is the physical 
masking, which is accomplished by placing the mask of desired shape on the substrate. We 
Fig. 2.2: Experimental set up of spray pyrolysis technique. 
A = Lower tube G = Graphite block H = Heater S = Substrate
P = Upper tube T. C. = Thermocouple F = Beaker
P 
Air 
A 
G 
-S 
-F 
T.C 
H
hh 

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found mica and stainless steel as suitable masking material. Since the thickness of the films 
deposited is of the order of several nanometers the mask should be as thin as possible so as to 
obtain uniformity of thickness throughout the film pattern. Masks of different size and shape 
were prepared for electrical and optical measurement and one of them are shown in Fig. 2.3. 
Air Compressor 
An air compressor is a device that converts power usually from an electric engine into 
kinetic energy by pressurizing and compressing air, which is then released in quick bursts. It 
is a reservoir type electrical air compressor. A rotary pump in this section mode draws 
atmospheric air and keeps it reverse in a large capacity air tank. At the outlet of the tank a 
pressure gauge is attached which records the pressure of the air at the time of supplying it 
from the tank. There is a bypass control valve which can keep the output pressure constant. 
Heater 
The heater H is an ordinary hot plate 2-kilowatt nichrome wire heater. The top of the 
plate is covered with a thick sheet of stainless steel plate G shown in Fig. 2.2. Substrate is 
placed on this plate G to have a uniform temperature throughout the substrate surface. A mica 
sheet with the same design of mask is placed in between the substrate and the mask to 
prevent spreading in solution beyond the opening of the mask. The heater power is controlled 
by an electrical voltage variac. The temperature of the heater was measured by copper 
constantan thermocouple tightly attached to the substrate surface placed on the heater plate.