Texturing and properties in hot forged SBN63/37 ceramics

Strontium barium niobate (Sr,Ba)Nb2O6 ferroelectric ceramics were obtained through two stage process, a lower temperature conventional sintering and a higher temperature hot forging. The objective was directed to the microstructural texturing of SBN bulk ceramics for the enhancement of its electrical properties taking advantage of the large crystallographic anisotropy of this system. Scanning electron microscopy revealed that high-density and crack-free ceramic bodies with a partially textured microstructure could be achieved following the proposed procedure. The grains were found laying in their lengthwise direction in the plane perpendicular to the pressing axis. An effective Lotgering factor of 40% was observed by the X-ray diffraction analysis at room temperature. Dielectric permittivity and losses were measured as a function of the temperature. The results showed a dielectric anisotropy when ceramics were measured in different cuts, which were related to the effective spontaneous polarization that is higher in the perpendicular direction than in the pressing direction, as verified in the hysteresis loop measurements. This fact is expected since the SBN polar axis is in the [0 0 l], which is the same of the grain lengthwise.