you can apply dc voltage (5 to 20 V dc), in air across the PZT thin film capacitor. The dc voltage to be selected depends upon the thickness of the film. Calculate the dc voltage which is equivalent to two or three times the coercive field (obtained from PE hysteresis loop measurements. Keep track of the leakage current while poling so that the film remains insulating. Try to keep your electrode area small. Hope fully there should not be any cracks or pin-holes in your film.

Now, whether the sample is poled or not can be seen through dielectric measurements and piezoelectric measurements carried out before and after the poling treatment.

For measuring hysteresis loops on thin films, it is very easy, all yooou need is an Oscilloscope, a function generator capable of giving sine waves of upto 20V output, select a frequency of 50 HZ, and make us of a Sawyer tower circuit, which is very easy to build for such low voltages.

If you have a digital storage oscilloscope you can record the hysteresis loop, and also store the data.

Thanks! I already have a ST circuit to measure hysteresis loops.

I'm having problems to know if the sample was effectively poled. How can I see that in dielectric measurment?

Thanks for your answer!!!!

What do you mean by effectively poled. Are you looking for a certain property which can vary after poling. If yes, Then try to measure that property before and after poling.

Try to see if there is a change in the dielectric constant before and after poling.

Try to do X-ray diffraction before and after poling (of course you may have to remove the electrodes for this).

Try to check the piezoelectricity before and after poling

Try to measure the pyroelectric currents before and after poling.

Thanks!