i have prepared metal oxide nanoparticles in powder form now i want to take dielectric studies on my samples. whether powder sample is enough or make it any pellet form for this studies also mention name of the technique.
Difficult to do dielectric studies on powder samples.
For dielectric studies you need to make a capacitor., which means the power has to be compacted in the form of a circular disc (then sintered) to prepare a ceramic disc, and then electrodes have to be applied on opposite faces. Thei makes a metal-insulator-metal capacitor.
K. Sreenivas
As Prof.K. Sreenivas said, it is not possible for powder samples. You need to make pellets of particular diameter as required by the impedance analyzer.
Hello
You can have a first idea of the dielectric behaviour of your nanoparticles by simplypressing them in shape of pellets and measuring the electrical behaviour (for instance versus temperature) through 2-contact impedance spectroscopy.
This is helpful in case of ferrolectric compounds for which a transition is observed
(with a peak in the dielectric constant).
One precision: If you measure for instance between 100 and 500 K, measure the properties cooling down the sample. The problem of nanoparticles is the adsorption of water at room temperature that might niduce a non expected behaviour (conductivity rather high). By measuring on the cooling ramp, water adsorbed would have been desorbed and you will avoid this parasitic behaviour.
Hoping it helps.
Guilhem
I really like the suggestion of Dr. Dezeanneau, especially the advantage of starting the measurements from high temperature to low temperature. This drives away any moisture peaks. These peaks sometime really produce spurious behaviour and being to bother while interpretation.
K. Sreenivas
you can measure the dielectric performances of your powder samples at high frequency ( several GHz) on basis of resonance method.
You can measure dielectric properties of powder samples at microwave band (especially 8 - 12 GHz) in cylindrical cavity resonator with axial tube (for powder). The problems are: water absorption in powder and unsertainty in density of powder.
Dear Mr Rajesh,
yes of course it is possible to prepare the powder for dielectric measurements.
You must have a good measurement chamber in a wave guide device and use please the ASTM standard. You can calculate the eps ´and eps ´´ loss .
All the best
F. Gräbner
Hi
Powder samples are pressed into pellets or disk then sintered at recommended temperature so that it is strong. You can apply PVA or any related binder that evaporates at low sintering temperature during compaction.
After that, you can use EIS or impedance analyser to obtain capacitance and type of conductor of your pellet by plotting 1/C^2 against polarisation. This is the mott-schottky. you can use the capacitor and dielectric formula with circular area.
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