The studies of ferroelastic phase transitions and domain walls in KMgCl3 crystal

The ferroelastic phase transitions of KMgCl3 crystal grown by the Czochralski method were investigated by direct observation using a polarizing microscope with varying temperature, The results showed that the KMgCl3 crystal undergoes two pure ferroelastic phase transitions from cubic prototypic phase to tetragonal, and to orthorhombic structure at about 312 degrees C and 224 degrees C, respectively, and can be classified into m3mFmmm(p) species. The permissible domain walls of this species were analyzed by both the strain tensor and group theoretical method.