Domain evolution with electric field and delineation of extrinsic contributions in (K, Na, Li)(Nb, Ta, Sb)O₃ single crystal

Extrinsic contributions play an important role in the functionalities of ferroelectric materials, while domain structure evolution is crucial for understanding the extrinsic dielectric and piezoelectric responses. In this work, domain configuration changes with an electric field applied along [001]_C in the tetragonal (K, Na, Li)(Nb, Sb, Ta)O₃ single crystal were studied by means of polarizing light microscopy. Results show that parts of the spontaneous polarizations in the (001)_C plane are switched to [001]_C direction, while others still stay in the (001)_C plane due to high induced internal stresses. Single domain state cannot be achieved even under a high electric field. After being poled along [001]_C, the volume fraction of domains with polarzations in the (001)_C plane is still about 25.2%. The extrinsic contributions to the dielectric constant are 15.7% and 27.2% under the E field of 1 kV/cm and under 2 kV/cm, respectively, estimated by the Rayleigh analysis.