1- After powder preparation at 550 C, is it necessary to anneal it again at a higher temperature (like 700 C)?
2- is in necessary to wash powder?
I have developed one, there is no response to ethanol nor acetone. I'd like to know the possible problems. I have tried different working temperature.
Electrical measurement are difficult on powders, and cannot be done.
gas sensing is normally sees as a resistivity change.
Therefore it is important that you press you powder into a small dense pellet, and aply electrodes to it. so that you can measure the change in electrical resistance/conductance when it is sensing a target gas of a certain concentration.
Moreover gas sensing has been seen to offer a high sensitivity at a certain temperature, so therefore you need to heat you pellet also.
As Sreenivas Sir said, gas sensing studies are done on pellets and also on thin films. A greater surface to volume ratio (as in thin films) is expected to give better sensing results. SO in case you have the powder sample ready, u can make pellets using a pellet presser (0.5gms should work). The make electrodes using silver paste and do the electrical studies,
1. Higher temperature annealing results on bigger particle size.
U can make a pellet from the powder you obtain.
We could not measure the resistance of the powder films. We had finally used the sol to develop thin film gas sensors.
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