I am recently using Polarization vs Electric field hysteresis loop tracer (PE loop tracer) instrument.The instrument provides good values of remnance and coercive field for reference that came with instrument but it shows different shape features for the reference standard PZT and also similar loop for another sample. But the loop shape is not the way it should be. I have attached one data plot I got.Can anyone suggest is it genuine and if not how to improve it?
Unable to see your data plot - not able to download or see it.
Please upload it again.
Pl confirm Are you measuring P-E loops on thin films or bulk PZT ceramics.
K. Sreenivas
I am measuring the PE loop of bulk sample pellets with silver as conducting electrodes
Well I saw the plot now. Yes the perfectly horizontal lines showing the saturation is a little difficult to accept.
Your plot shows a very high spontaneous polarisation (80 micro C/cm2)
For a PZT pellet, the measured polarisation value seems to be too high. PZT does not exhibit such a large polarisation.
PbTiO3 does show such a large polarisation, but its coercive field is normally high.
Your measured value is a quite a high value, and depends on which material you are measuring this.
Definitely the integrating capacitor should be large enough compared to the sample capacitance during PE measurements.
Are you determining the area correctly in your case.
1) First advise is to repeat the measurement on some other machine for the sample.
and confirm.
One clarification sir the plot is for La doped BiFeO3 and not for PZT.For PZT I am getting simillar plot with value around 20 microcoulomb/cm2.Area is correctly measured and for larger capacitance almost circular loop is coming. The suggestion I will follow it up Sir.Thank you
If you are ausing an automatic PE hy loop measurements, then
some in put parameter is not being set properly.
yes Sir.It is automatic only. Can you please help me out in fixing this problem i.e in what way It should be adjusted.
As I already mentioned about the issues I am facing while operating PE loop tracer, I am herewith attaching the plots I got for Bi2Fe4O9 sample which is drastically different from literature. Specifically while adjusting Resistance and capacitance value I am observing anomalies(like a step in the first plot).what does these deviations imply. can anyone suggest me in this context.
There may be some polarisation. Firstly the shape of the loop clearly indicates that the contacts are not good on either side of your ferroelectric capacitor. Secondly it is important to have a high DC resistivity, and ac resistivity as well (especially at lower freqnecies (1 to 100 Hz). In any case the dc resistivity (which almost represents for 0 Hz) will give you a good idea, the higher this value the most resistive will be your samples, and the leakage currents will be low, and you may be able to measure a good saturating hysteresis loop.
You can do one thing just cool down your sample with a a little bit of liquid nitrogen, and measure the hysteresis loop, this would definitely lower the resistivity of your sample significantly, and you may be able to observe a good hysteresis loop.
K. Sreenivas
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