By means of electron paramagnetic resonance, it was shown that defect dipoles were aligned, along the direction of spontaneous polarization in polycrystalline ceramics, by subjecting capacitors to a direct-current bias at high temperatures. The alignment was revealed by orientation-dependent electron paramagnetic resonance signals from the polycrystalline perovskite lattice. The alignment of the defect dipoles was found to increase the light sensitivity of the defects.

W.L.Warren, D.Dimos, G.E.Pike, K.Vanheusden, R.Ramesh: Applied Physics Letters, 1995, 67[12], 1689-91