Processing and Properties of Textured Potassium Strontium Niobate (KSr₂Nb₅O₁₅) Ceramic Fibers – Texture Development

Abstract

Highly [001] textured KSr2Nb5O15 (KSN) ceramic fibers were fabricated by a combination of novel alginate gelation method and templated grain growth using acicular KSr2Nb5O15 template particles. The needle‐like KSN template particles were prepared by molten salt synthesis method with salt/powder ratio of 2 giving the highest aspect ratio. Fibers were extruded into CaCl2 salt solutions from alginate‐based slurries without or with 10 wt% KSN template particles using a nozzle with 2 mm diameter and 80 mm length. Varying sintering temperature from 1300°C to 1450°C and time from 2 to 6 h were found to increase the texture. A maximum degree of orientation, ƒ(00l), of 0.95 was obtained, as measured by Lotgering factor, and a grain orientation distribution, r, of 0.28 was obtained as measured by rocking curve analysis.

Sodium niobate particles with controlled morphology synthesized by hydrothermal method and their use as templates in KNN fibers

“…The fibers were drawn using a novel fiber drawing technique called alginate gelation method which was developed by our group [4,15,18]. Alginic acid sodium salt from brown algae (Sigma-Aldrich) was used as the Na-alginate source for this study.…”

“…During tape casting, these template particles in the slurry are aligned along the casting direction due to the shear action under doctor blade. At high temperatures, the growth of preferentially aligned template particles at the expense of the fine matrix particles yields highly textured microstructure with anisotropic properties [16][17][18].…”

“…Fabrication of lead-free materials with crystallographic texture is the main approach to enhance their properties [6,16,17]. Textured ceramics can be produced by various processing methods such as, hot pressing, hot forging, or templated grain growth (TGG) techniques [16][17][18]. TGG is usually the method of choice instead of the other processes which are more expensive.…”

Electrical Properties of 1–3 Piezocomposites Prepared from Textured KSr2Nb5O15(KSN) Ceramic Fibers

“…Slurries without template particles were also prepared to obtain randomly oriented fibers for comparison. Details of the synthesis of KSN template particles and KSN fibers were given elsewhere [6].…”

Growth of NBT template particles through topochemical microcrystal conversion and their structural characterization

“…These methods provide crystallographic orientation especially in perovskite structure along 〈001〉 direction. 3 Anisometric needle-like 4 and platelet-shaped 5 microcrystal particles are suitable for crystallographic orientation by TGG and reactive RTGG techniques. 6 Shape and aspect ratio of template particles have strong effect on grain orientation.…”