Growth of lead-free piezoelectric 0.45BZT–0.55BCT single crystal and investigation of dielectric, polarization and birefringence properties

•Single crystals of 0.45BCT–0.55 BZT are grown by spontaneous nucleation.•Temperature dependent birefringence of the material is reported for the first time.•In-situ observation of phase transition by polarized light microscope carried out.•Anomaly in dielectric, birefringence and polarization measurements is observed.•It is attributed to the formation of macro-domains below 103 °C.

Single crystals of 0.45BZT–0.55BCT were grown by spontaneous nucleation technique. The X-ray diffraction shows that grown crystals possess tetragonal symmetry with c/a=1.009. The dielectric constant shows anomalies near 109 °C and 2 °C corresponding to cubic-to-tetragonal and tetragonal-to-rhombohedral phase transitions, respectively. In addition, an abrupt non-dispersive decrease in dielectric constant was observed near 103 °C. Temperature dependent birefringence and remnant polarization measurement also show a sharp decrease near 103 °C. This anomaly in dielectric, birefringence and polarization measurements is attributed to the formation of macro-domains below 103 °C. Investigation under optical microscope showed that the crystals have optical birefringence ∼0.051 and are negative uniaxial at room temperature.