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.