It was reported that there was evidence of a significant increase in bulk dislocation density upon poling this polycrystalline material. Synchrotron high-resolution X-ray diffraction measurements yielded a dislocation density which was of the order of 109/cm2, and an associated strain energy increase of about 20kJ/m3. This implied that the application of an external poling field generated defects in the structure and increased the internal stress. Diffraction-line-broadening analyses revealed large microstructural changes, especially along the direction of spontaneous polarization and poling-field vector. The inhomogeneous strain upon poling was of about the same order of magnitude as that caused by electrostriction during poling, and indicated a substantial increase in the dislocation density. The dislocations were likely to form low-angle boundaries in order to relieve some of the internal stresses. However, the overall effect was an increase in inhomogeneous strain upon poling in spite of the fewer 90º domain walls.

Dislocation-Density Changes upon Poling of Polycrystalline BaTiO3. D.Balzar, H.Ledbetter, P.W.Stephens, E.T.Park, J.L.Routbort: Physical Review B, 1999, 59[5], 3414-20