A new ferroelectric: La2Ti2o7

Abstract

Ferroelectricity was observed in a lanthanum titanate single crystal (La2Ti2O7), a monoclinic crystal of the space group C22-P21. The Curie temperature was found to be about 1500°C. It was determined by a D-E hysteresis loop at room temperature that the spontaneous polarization Ps = 5 μC/cm2 and that the coercive field Ec = 45 kV/cm. Ferroelectric domains were observed using a crystal etched by an aqueous solution of nitric acid. The La2Ti2O7crystal showed strong piezoelectric and linear electro-optic effects: electromechanical coupling factor k22 = 0.29; half-wave voltage [E l]δ/2 = 2000 V at a wavelength of 6328 A.