Preparation And Electric Properties Of NBT-KBT Lead-Free Pizoelectric Textured Ceramics

It is imperative under the situation of increasing enviromental protection worldwide that investigating of lead-free piezoelectric ceramics to replace traditional piezoelectric ceramics is the latest trend in piezoelectric development. In this paper, as a lead-free material, sodium bismuth titanate-potassium bismuth titanate (NBT-KBT) ceramics was fabricated by Reactive Templated Grain Growth (RTGG) technique with the Bi₄Ti₃O₁₂ particles as template. Effects of processing parameters, Such as template materials selection and processing, preparation equipment and method of textured ceramics, relationship between microstructure and electric properties of NBT-KBT ceramics were investigated. NBT-KBT textured ceramics with better properties and strong anisotropy was prepared.The principle of selecting template particles to prepare textured ceramics was analyzed according to technic properties of RTGG and TGG, templated type of adapting to prepare NBT-KBT textured ceramics was confirmed. Plated-like Bi₄Ti₃O₁₂ template particles with high aspect ratio was used to prepare NBT-KBT textured ceramics; according to comparing the current ceramics preparation method, molding technics for preparing NBT-KBT textured ceramics was optimized and the molding equipment was designed, it had been applied for national patent of practicality new pattern. (application code: 200520078348. 9)Anisotropic Bi₄Ti₃O₁₂ particles were synthesized by molten salt process. Effect of technique and processing parameters on the morphology of Bi₄Ti₃O₁₂ particles were also investigated in detail. They were determined by the sintering temperature, molten salt content and soaking time. Excessive Bi₂O₃ content played an important role in morphology and scale of Bi₄Ti₃O₁₂ particles, so effect of the degree of excessive Bi₂O₃ content and processing parameters on the morphology and scale of Bi₄Ti₃O₁₂ particles were investigated in particular. Pure Bi₄Ti₃O₁₂ particle powders, which possess high aspect ratio, were synthesized by molten salt process. The obtained pure Bi₄Ti₃O₁₂ particle powders are very suitable for tape-casting. The average size of pure Bi₄Ti₃O₁₂ particles is 8～10μm in diameter and 1～2μm in thickness. Based on this particles, Bi₄Ti₃O₁₂ ceramics with anisotropy was prepared, relationship between electric properties and process parameter were investigated.NBT-KBT ceramics was prepared by traditional process, and the morphotropic phase boundary (MPB) was confirmed, the component of 0.84NBT-0.16KBT ceramic is closed to MPB and has better piezoelectric properties; Effects of template Bi₄Ti₃O₁₂ concentration on the microstructure and piezoelectric properties of NBT-KBT ceramic were studied. The processing parameters were optimized.The textured NBT-KBT ceramics was fabricated by dry tape-casting method and...