So we apply a final trick: heat the piezoelectric to a very high temperature while a strong electric field is applied. The ionic bonds will not only bend, they will actually rearrange themselves.
Here we apply a voltage to the outside edge of the tube, and the opposite voltage to its inside edge. In the oven, bonds then rearrange themselves so that the negative (blue) ends of all the Z's face outwards. It is as if we rotated all of the crystallites (although, in fact, this only requires minute atomic rearrangements). Cooling locks this final arrangement in place.
