Preparation and morphology of anisometric KSr_2Nb_5O_(15) particles

摘要

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 KC1 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 mu m in length and 2-4 mu m in diameter are ideal templates for fabricating textured ceramics with tungsten bronze structure. Growth mechanisms in MSS method were also proposed in this work.