Distinctive Nb–O hybridization at domain walls in orthorhombic KNbO₃ ferroelectric perovskite

Niobate-based ferroelectric perovskites have been an important group of functional materials. Since the formation and dynamics of domain walls are decisive to the properties of ferroelectrics, in this study, a representative orthorhombic niobate-based ferroelectric perovskite, i.e., KNbO3, is studied by using first-principles calculation. Three types of domain walls with permissible walls located at crystallographic planes, including uncharged 180 & DEG;, 120 & DEG;, and 90 & DEG; domain walls, are selected for simulation. The formation energy, intrinsic energy barrier of domain-wall motion, and the electronic configuration are systematically analyzed. We discover that the formation energy is associated with the variation of Nb-O hybridization at the domain wall, while the intrinsic energy barrier of the domain-wall motion depends on the dynamical change of Nb-O hybridization along the transition path. Therefore, we propose that the Nb-O hybridization plays a critical role in the formation and motion of domain walls in niobate-based ferroelectrics.