Local and electronic structures of NaNbO₃, AgNbO₃, and KNbO₃

Abstract

NaNbO3, AgNbO3, and KNbO3 with ABO3-type perovskite system is known to possess good ferroelectric properties. Using the traditional average structure, a change in the A-site ion size leads to a change in the tolerance factor. We directly determined the rattling space of A-site ions by analyzing the local structure, which was affected by the change in ion size. The analysis of local structure, using a collaboration of a pair distribution function and extended X-ray absorption fine structure, revealed that the bonding sites with large fluctuations varied depending on the ion size.Experimental evidence strongly suggests that the A-site ions are hybridized with oxygen, as our observation revealed a change in the chemical bonding state of the A-site ion with the nearest cation of oxygen.