It depends on the material, typicaly for PZT family, we use the silicone oil at a temperature of 150C and an electric field of >=2.5 kV/mm for 30 minutes, and cooling to 30C with electric field.

Of course you can use sophisticated poling techniques i.e. the change the polarization of the polarization field, pulse technique but looking at publications, people use the simplest technique of polarization.

May be the best start (look references also) with:

Hong-Wen Wang, Syh-Yuh Cheng, Chien-Min Wang "Optimization of poling process for piezoelectric PZT ceramics"

doi: 10.1109/IEMTS.1989.76153

Thank you Dr. Wawrzala for your attention towards this question. I followed the same usual techniques as you said. However, still one question remains, how do we know that sample has reached to its optimum poling condition. I mean, would it be right to say if the phase angle reaches as close to 90 degree, it is well poled ??

I would appreciate if you kindly give your comments.

thanks again,

You may pole the samples at several fields and check for the response say kp and d33.

The optimum poling will give maximum response.

Otherwise you may keep the poling field just below the breakdown strength of the material which you may check by breaking a pellet by slowly increasing the poling field strength.

I have poled the samples even upto 40 kV/cm in silicone oil bath without any problem.

Dr Mitra: What is your scientific problem - you want to build a framework to the optimization of poling processes?

@Dr. AK Singh, thank you sir for your answer, even I did upto 7kV/mm for my sample in silicon bath at 150 C, quite below its Tc.

@Dr. Wawrzala,

Sir, I'm currently trying to develop a new lead-free solid solution, therefore, yes I'm trying to optimize all the influencing parameters of poling to get maximum piezoelectric properties.

To optimize poling conditions you have to measure relative dielectric permittivity, d33, kp or all other piezoelectric constants versus the applied DC electric field. You have to do so for by changing the time applied for the poling. You need for this study a high voltage DC generator and the sample must be in silicon or oil bath. You need also many samples fabricated in the same conditions to this study.

The values of d33, electromechanical coupling factor, and other piezoelectric properties are found to saturate when the samples has reached optimum poling condition.

Thank you both Dr. Kobor and Dr. Chang for addressing the question....

we need an automatic current controlling system to measure the weak current when poling prior to breakdown. The optimal poling condition is to pole the ceramic near breakdown strength. the dipoles will rotate completely.

Poling voltage should be about 2 to 3 times the coercive voltage.

If you pole at high temperatures (say 100 to 150 deg C) in an oil bath, the poling voltage will reduce.

Monitoring the current through the sample during through the sample is always useful, and keep the currents as low as possible ( I would) put the current limit at 10 to 15 micro amperes). 

Duration can from 30 minutes to 1 hour.

and Keep the field on while the sample is being colled from 100 to 150 deg c. , back to room temperature.

Dont touch the sample with hands soon after electrical poling. You will get a shock of your life sometimes.

Pick it up with plastic tweezers, and slowly wrap it up in an aluminum foil, carefully with the plastic tweezer.

K. Sreenivas

Dear Dr. Sreenivas,

thank you giving the detail technique of poling, however few questions remain in my mind, is it good to cool the sample faster with field on and secondly, how to monitor such low current passing through the sample.

Thank you again for spending your time and energy to address my query.

Supratim

1) I normally do slow natural slow cooling under applied poling field.

2) You can have an ammeter in series (0-10 micro amp, or 0-50 micro amp)

connected in series with you dc power supply and the sample being poled.

Dear Supratim

Follow the following discussion for more information about poling

https://www.researchgate.net/post/How_to_do_poling_of_pellets_for_ferroelectric_measurements_After_poling_within_how_much_time_we_have_to_do_our_ferroelectric_measurements

https://www.researchgate.net/post/How_can_I_increase_the_piezoelectric_constant_If_I_give_the_same_poling_field_to_all_the_prepared_samples_Is_it_a_correct_method

Check the following articles and back references

https://www.researchgate.net/publication/273446569_Poling_electric_field_dependent_domain_switching_and_piezoelectric_properties_of_mechanically_activated_Pb092La008Zr060Ti040O3_ceramics

Article Optimization of poling parameters of mechanically processed ...

Regards

Dear Supratim Mitra

The poling process of piezoelectric ceramics materials can be carried out to align the net polarization in a direction of applied high DC voltage. The net polarization alignment is dependent on the poling conditions of field biasing, temperature and biasing time. The poling conditions is altered from ceramics materials to others, i.e it is vary with the type of piezoelectric ceramics. To start with optimizing the poling condition it is very important to synthesis a good and dense piezoelectric ceramic, to know the phase transition, to know the coercive field and the breakdown voltage. Generally, the higher biasing field approximately 2Ec results in more complete polarization. Similarly, longer poling duration and higher poling temperature (less that Tc) derive better piezoelectric properties.

Regards

Hello

is there any results such as plots for d33 versus poling voltage?