Ferroelectric and electro-optical properties of SCNN single crystals

Single crystals of A-site filled Pb-free ferroelectric tungsten bronze composition Sr2NaNb5O15-Ca2NaNb5O15 (SCNN) With orthorhombic (pseudo-tetragonal) tungsten bronze structure have been grown by the Laser Heated Pedestal growth technique successfully. The dielectric, pyroelectric and thermal expansion properties of the grown SCNN crystals have been investigated in the temperature range of 90 to 700K and frequency range of 10(2)-10(6) Hz. Mechanism for the low temperature dielectric relaxation has been discussed. The spontaneous polarization and the pyroelectric coefficient are found to be large at RT, 35muC/cm(2) and 5x10(2) muC/(m(2)-degreesC), respectively. The electro-optic coefficient r(33) and r(31) are measured using both modified Mach-Zender interferometer and Senarmont methods.