The effect of machining on domain configuration in [001]-oriented tetragonal Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ single crystals

Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PMN-PT) single crystals have attracted increasing attention in electro-optic and nonlinear optical applications. In this paper, it was found that the domain configuration of PMN-PT single crystals was influenced by machining and electric process, such as cutting, grinding, polishing, and electrical field poling. The ordered herringbone/stripe domain pattern can be changed into an unexpected disordered domain state in tetragonal PMN-PT crystals which was observed in some crystal samples. Those chaotic structures can decrease transmittance and increase possibility of cracking during poling. However, the disordered domain pattern can be eliminated by a temperature cycling process. Crack-free single-domain crystals were successfully obtained by electric field poling, exhibiting complete optical extinction in an orthogonal polarized light microscope. The results suggest that the domain configuration of PMN-PT single crystals is sensitive to machining process and can be controlled by proper temperature and electric field.