A study of ferroelectric domain patterns in orthorhobic KNbO₃ with optical microscopy

Ferroelectiric domain patterns in natural surface layers of Czochralski as‐grown crystals are very complicated. The inner domain patterns are comparatively simple and consist of a regular arrays of so‐called thin lens‐like 90° domains. Only few inner 60° and 120° domains crossing the 90° domain arrays are observed. The inversion or 180° domains are shape‐like separated islands. The 60° microdomains are easily introduced into the surface layers during the specimen processing. There are some elastic interactions between the different kinds of ferroelectric domain walls, the orientations of which are in good coincidence with the theory proposed by Janovec.