Formation of self-assembled nanodomain structures in single crystals of uniaxial ferroelectrics lithium niobate, lithium tantalate and strontium-barium niobate

摘要

The formation and evolution of the self-assembled nanodomain structures during polarization reversal have been comparatively analyzed in single crystals of various uniaxial ferroelectrics: LiNbO_3 (LN), LiTaO_3 (LT) and Sr_xBa_(1-x)Nb_2O_6 (SBN). Several experimental methods have been used for visualization of the micro- and nanodomain patterns. The static domain images have been obtained by optical microscopy and piezoresponse force microscopy. The Raman confocal microscopy allowed us to obtain the domain images in the bulk. The equilibrium slow switching with effective screening resulted in growth of polygon-shaped micro-domains: hexagons in LN, triangles in LTand squares in SBN, which corresponds to crystal symmetry. Switching in nonequilibrium conditions (noneffective screening of depolarization field) brings to appearance of similar nanodomain structures in all studied crystals as a result of different processes: (1) formation of nanodomain ensembles, (2) discrete switching, (3) incomplete merging and (4) spontaneous backswitching.