Abstract
Layer-structured ferroelectric bismuth titanate (BiT) has attracted much attention as a promising material for Pd-free piezoelectric devices and RRAM. Since the spontaneous polarization (Ps) vector lies away from the a axis to the c axis by about 4-5 deg, Ps appears along the c axis (Ps(c)) as well as along the a axis (Ps(a)). Although the elucidation and the control of domain structures of ferroelectrics are crucial in view of their practical applications, the domain structure of BiT still remains unclear. We have observed the three-dimensional domain structures by scanning probe microscope (SPM) as well as the domain dynamics induced by electric field with optical microscopy. SPM observations revealed that the domains induced by Ps(c) are formed in Ps(a)–related 90-deg domains. Optical observations of interference colors enabled us to determine the directions of Ps(a) in 90-deg domain dynamics. Ps(c) domain dynamics were investigated by viewing interference colors in the a-b plane of tilted crystals.
