THE STUDIES OF FERROELASTIC PHASE-TRANSITIONS AND DOMAIN-WALLS IN KMGCL3 CRYSTAL

The ferroelastic phase transitions of KMgCl3 crystal grown by the Czoc hralski method were investigated by direct observation using a polariz ing microscope with varying temperature, The results showed that the K MgCl3 crystal undergoes two pure ferroelastic phase transitions from c ubic prototypic phase to tetragonal, and to orthorhombic structure at about 312 degrees C and 224 degrees C, respectively, and can be classi fied into m3mFmmm(p) species. The permissible domain walls of this spe cies were analyzed by both the strain tensor and group theoretical met hod.