The tetragonal tungsten bronze (TTB) type of Sr,Bal-,-Nb206 (SBN) (0.5 5 x 5 0.75) was synthesized by a mixedoxide 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-I at 600, 1450, and 2000 nm, respectively. The linear electrooptic coefficients for SBN55, r33 and rI3, were 46 X lo-'' and 21 X lo-'' m/V at 633 nm, respectively. [

Fabrication of Optically Transparent and Electrooptic StrontiumBarium Niobate Ceramics.-SrxBa1-xNb2O6 ceramics with 0.5 ≤ x ≤ 0.75 having the tetragonal tungsten bronze (TTB) structure are prepared by a mixed-oxide route followed by a two-step densification process (pressureless sintering and hot isostatic pressing in a 20% O2/argon mixture). All singlephase TTB-type ceramics show the characteristics of relaxor ferroelectrics. Some pellets are transparent; the extinction coefficients of the sample with the highest transparency are calculated to be 30.4, 5.8, and 2.4 cm-1 at 600, 1450, and 2000 nm, respectively. The linear electrooptic coefficients for the ceramics are about 10% of those for single crystals. For the sample with x = 0. 55, r33 and r13 are 46·10-12 and 21·10-12 m/V at 633 nm. -(VANDAMME, N. S.; SUTHERLAND, A. E.; JONES, L.; BRIDGER, K.; WINZER, S. R.; J. Am.

Ceramic processing offers a major advantage over single crystal growth in that large and complex shapes can be formed. This is especially important for electrooptic applications involving large apertures because single-crystal electrooptic materials are only available in diameters up to 3 cm. Tetragonal tungsten bronze strontium barium niobate (SrxBal-xNb206) was synthesized by both a mixed oxide and sol-gel route. By using the two-step process of pressureless sintering followed by oxygen hot isostatic pressing (HlPping), transparent ceramics were formed. Microstructural, dielectric, piezoelectric, optical, and electrooptic properties were investigated.