A Study of 90°Ferroelectric Domains in Potassium Tantalate Niobate Crystals by Means of Transmission Electron Microscopy

By flux method, potassium tantalate niobate crystals with 46% Nb contents were prepared. In this material 90°a-type domains with (011) and (01 ī) walls were observed by a transmission electron microscope, and the nature of fringe patterns associated with these domain walls was analysed. According to the extinction rules for the domain walls, the displacement vector R along < 01 ī > direction can be determined. Finally, using a selected area electron diffraction method, we examined the crystallographic character of these 90°domains and defined the ratio of lattice parameters c to a.