Anisotropic Ferroelectric Properties of Tungsten Bronze (Sr_1.9Ca_0.1)_1-xBa_xNaNb₅O₁₅ (x = 0 and 0.5) Ceramics

Abstract

Tungsten bronze family ferroelectrics are attractive materials for use in electro-optic, pyroelectric and piezoelectric devices. In this work, we prepared dense tungsten bronze ceramics with the compositions of (Sr1.9Ca0.1)1-xBaxNaNb5O15 (x = 0 and 0.5), by spark plasma sintering at 1200oC for 5 - 60 min under 35 MPa in vacuum. Ferroelectric properties (dielectric constant and polarization) were measured on parallel- and perpendicular-cut samples, and anisotropic properties were observed. The dielectric constant of (Sr1.9Ca0.1)0.5Ba0.5NaNb5O15 is 2685 at the curie temperature for the parallel-cut sample, whereas it is 1411 for the perpendicular-cut sample.