CTR ADV STUDIES SCI & TECHNOL MICROSTRUCT,NANJING 210093,PEOPLES R CHINA
; SHANDONG UNIV,INST CRYSTAL MAT,JINAN 250100,PEOPLES R CHINA
; INST HIGH ENERGY PHYS,BSRL,BEIJING 100039,PEOPLES R CHINA
Domain configurations and structures of ferroelectric KTa1-xNbxO3 crystals in both orthorhombic and tetragonal phases are studied by a polarizing microscope. It is found that the domain patterns vary in plates of different thicknesses. The domain evolution and new phase nucleation during the first-order orthorhombic-tetragonal-cubic phase transitions with large thermal hysteresis are directly observed under polarized light. The emergence of a large number of microdomains upon cooling is revealed and discussed.