M_C Type Phase Structure and Temperature-Induced M_C-C Transition in the As-Grown PMN-0.36PT Single Crystal

The phase structure in the as-grown PMN-0.36PT single crystal was studied and the temperature-induced domain evolution was investigated using a polarized light microscope (PLM). The crystal is identified to be M_C type monoclinic based on the PLM results and tends to transform to cubic (C) phase directly through polarization rotation. The M_C phase is metastable below Curie temperature (T_C), but prone to tetragonal phase upon electric field poling or high-temperature annealing. We suppose that the formation of the M_C phase structure is associated with the strain gradient originated from Ti⁴⁺ segregation and the special M_C-C phase transformation style is mediated by the corresponding residual ferroelastic strain stored within the as-formed domain structure.