Preparation and morphology of anisometric KSr 2Nb 5O 15 particles

Abstract

Anisometric KSr 2Nb 5O 15 (KSN) particles were synthesized by conventional mixed-oxide (CMO) method and molten salt synthesis (MSS) method, respectively. In MSS method, preparation of KSN was carried out in both SrCO 3–Nb 2O 5–K 2CO 3–KCl system (system I) and SrNb 2O 6–Nb 2O 5–KCl system (system II). The results revealed that the single-phase KSN obtained by CMO method was clumped and without obvious acicular morphology, making it difficult to use in texturing processes. In system I, though acicular KSN particles were synthesized by controlling the amount of KCl salt, they were easily contaminated by the presence of blade-like Sr 2Nb 2O 7. In contrast, pure KSN particles with high aspect ratio and uniform size were successfully synthesized by controlling the ratio of SrNb 2O 6/Nb 2O 5 in the new system (system II). The obtained KSN particles which are 5–30 μm in length and 2–4 μm in diameter are ideal templates for fabricating textured ceramics with tungsten bronze structure. Growth mechanisms in MSS method were also proposed in this work.