The interactions between dislocations and ferroelectric domains in KNbO3 crystals

It is found that it is rather easy to introduce dislocations into KNbO₃. With transmission electron microscopy we have determined the slip plane to be (110) and the Burgers vector of dislocations to be [110]. Using hot stage in a JEM-200CX electron microscope, we have made in situ observations during phase transitions at 435°C (cubic-tetragonal) and 225°C (tetragonal-orthorhombic). We have found evidence indicating the interactions between dislocations and ferroelectric domains. Especially during phase transitions, the new ferroelectric phase first appear in the vicinity of dislocations showing that the stress field of dislocations may raise Curie point of the crystals.