I'm trying to set up a electrical polling field that produces 2000 V/mm inside a kiln

Question

I'm attempting to produce my own piezoelectric ceramic materials.

I wish to manufacture half dollar size x 1/4" thick ceramics which are kiln fired at just under 1020 degrees Fahrenheit while exposed to a 2000 V/mm linear uniform electric field. Applications of this sort are carried out in the semiconductor industry - I'm trying to do something similar with home manufactured or assembled equipment.

I am looking for information and/or advice on how to achieve this. I am seeking details of appropriate wire sizes and spacings and of circuit diagrams and components suited to achieving the above described result. Information on suppliers of any specialist parts would also be welcome.

I would like to be able to place a half dozen or more discs in the oven at a time, so to achieve a uniform electric field it would ideally would need to cover the entire inside of the oven.

My understanding is that semiconductor industry solutions utilise a parallel plate capacitor and with the thin ceramics used, they seem to need close proximity of the parallel plates. I understand that it is preferable to have the probes make contact with the ceramic material.

Any information on how I can implement such a system on an amateur/ DIY basis would be welcome.

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Previously:

This is for half dollar size x 1/4" thick ceramics. I need wire sizes and components and schematics or suppliers for the outlined specs. I would like to be able to place a half dozen or more discs in the oven at a time so the electrical field ideally would be the entire inside of the oven. The temperature in the oven will be just under 1020 degrees farenheit. This is typically done in the semiconductor industry with a parallel plate capacitor and with thin ceramics yielding close proximity of the parallel plates. It is advised to have the probes make contact with the ceramic material. Thanks

Answer 1

Without the plates in good contact with the ceramic you'll get most of the voltage across the air gap since the relative permittivity of piezo materials is typically in the hundreds. Assuming the discs will be metalized, having that in contact with plates would do. Not much remains springy at 450C.. Maybe Inconel.

Note that some references have mechanical deformation applied along with the polarization field. See, for example, US2486560 (1946).

To answer at least part of your question directly, there is little current so wire size selection will be determined by corrosion considerations. In air, things like nichrome, Inconel, perhaps pure Ni, should be considered. Copper won't last long.

That field strength is very high- you'd need in excess of 12kV which his close to the dielectric strength of air for a 6.35mm gap. Perhaps you could arrange the mechanics so that no such gaps exist, or use a different atmosphere in the furnace.

Interesting question.. mostly materials science related.

Answer 2

More details would help us help you. Knowing what you really want to achieve, materials used, thickness would help. What do you know? Any references?

From what you describe it sounds "easy" [tm]. Just provide an HV DC voltage of the required voltage - probably a few kV, on metal plates and/or wires insulated as required to withstand over temperatures. Contact with material optional if enough HV available.

Getting from "just need" to reality needs more input from you.

Below are some links of POSSIBLE value to you. Nothing directly relevant to HV fields and firing but some may be useful.

• Video - have not watched but sounds highly relevant
• Barium titanate article from Wikipedia
• Polarization Processes in PZT Ceramics (PDF)
• Google Groups discussion

Fascinating:

• Barium titanate capacitor
• Barium titanate piezo material

When all else fails - something here may turn up a useful lead:

• Google search

Maybes:

• EVDL ceramic made barium titanate