FABRICATION OF OPTICALLY TRANSPARENT AND ELECTROOPTIC STRONTIUM BARIUM NIOBATE CERAMICS

The tetragonal tungsten bronze (TTB) type of SrxBa1-x-Nb2O6 (SBN) (0.5 less-than-or-equal-to x less-than-or-equal-to 0.75) was synthesized by a mixed-oxide route. Using the two-step densification process of pressureless sintering followed by oxygen HIPing, transparent ceramics were successfully fabricated. Microstructural, dielectric, optical, and electrooptic properties were investigated. All single-phase TTB-type SBN showed the characteristics of relaxor ferroelectrics. The extinction coefficients of the sample with the highest transparency were calculated from transmission spectra to be 30.4, 5.8, and 2.4 cm-1 at 600, 1450, and 2000 nm, respectively. The linear electrooptic coefficients for SBN55, r33 and r13, were 46 x 10(-12) and 21 x 10(-12) m/V at 633 nm, respectively.