We are using IET 7600 Plus Precision LCR meter in our lab for LCR measurements of different nanostructures (in pallet form). When we perform any measurement and repeat it within minutes, we get results with some changes. Is it due to some polarization which is induced in the sample when we apply electric field and it takes some time to be vanished after which we may get same results? Can any body please suggest me some reasons of this change ? Why can't we get same results?
Factors can affect are
1) Radiation polluted environment (Electro Magnetic field)
2) Change in temperature
3) Measuring instrument instability, especially at low level
4) Effect of Noise on measurement
The problem may not be of LCR meter.You can check it by measuring some standard capacitors. The samples which you are using in pellet form may have porosity and hence moisture may be affecting the capacitance and conductance.Measurements should be made in vacuum in such a case.Also check your connection.Shielded cables may be used to avoid stray capacitances.
Thanks for your suggestions Sir. We are not performing measurements in vacuum and air might be affecting the results.
Factors can affect are
1) Radiation polluted environment (Electro Magnetic field)
2) Change in temperature
3) Measuring instrument instability, especially at low level
4) Effect of Noise on measurement
because they are nanostructures thay are very sensitive to the variation of temperature and humidity. You can avoid these phenomena if you put for example your samples in isothermal box or in vaccum
@Abdelhalim Zekry Sir we are performing measurements of different metal oxide nanostructures. We use copper metallic contacts I.e. sample holder. We just give command for any measurement, LCR meter plots the corresponding graph and data table which is saved in USB and can be opened in excel. Both R and C change in each measurement.
Dear Mohammad,
According to my experience, you can get unreproducable results because of the following:
- Your cupper - pellet contact is not firm enough to make the contact impedance between the cupper electrode negligibly small compared to the impedance of the bulk of the pellet.such contact impedance depends on the pressure of the electrode and it contact area. So, any changes in the contact area changes the results
This can be treated by firmly pressing the electrodes to the pellet to make the contact impedance negligible or using deposited metallic electrodes.
The second cause is the appreciable leakage current on the side surface of the specimen. such surface current will be appreciable and comparable to the bulk currents in case of insulating pellet material. Such surface currents are really dependent on the surface contamination from the environment
The remedy is to to use guard rings to separate the bulk currents from the surface currents.
Wish you success
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