准同型相界内KNN-LS-BF无铅压电陶瓷的烧结与压电性能

采用传统的陶瓷工艺制备成分处于准同型相界(MPB)内的无铅压电陶瓷0.956K0.5Na0.5NbO3-0.004BiFeO3-0.04LiSbO3(0.956KNN-0.004BF-0.04LS),研究烧结温度对陶瓷的结构与压电、介电性能和相变温度的影响.研究结果表明:所有样品均为单一的钙钛矿结构；在1100℃以下烧结的样品的相结构均呈现明显的正交相与四方相共存的特征,同时略偏向四方相区;适当的烧结温度的提高,能促进陶瓷的致密化；随着烧结温度的升高,陶瓷的压电性能先显著提高后降低,陶瓷的介电损耗先降低后提高,但对正交相与四方相转变温度(θ0-1)和居里温度(θc)的影响比较小；当烧结温度为1100℃时,陶瓷具有最好的压电与介电性能,其压电常数(d33)高达297 pC/N,机电耦合系数(kp)高达54％,居里温度为355℃,tanδ为2.6％,这表明0.956KNN-0.004BF-0.04LS无铅压电陶瓷具有广阔的应用前景.

Sintering and piezoelectric properties of KNN-LS-BF lead-free ceramics among MPB composition

0.956K0.5Na0.5NbO3-0.004BiFeO3-0.04LiSbO3(0.956KNN-0.004BF-0.04LS) ceramics among the morpho-tropic phase boundary(MPB) composition were prepared by traditional ceramic processing.The effects of sintering temperature on the microstructure,piezoelectric,dielectric properties and phase transformation temperature of ceramics were investigated.The results show that the structure of all samples is a single perovskite structure,and also show the coexistence of little orthorhombic and main tetragonal phases,especially when the sintering temperature is below 1 100 ℃.The suitable increasing of sintering temperature promotes the densification of ceramics.With the increase of the sintering temperature,the piezoelectric properties of ceramics first increase evidently and then decrease while the dielectric loss first decreases and then increases.The sintering temperature has a little effect on θo-t and θc.When sintered at 1 100 ℃,0.956KNN-0.004BF-0.04LS ceramics have good electric properties: d33 = 297 pC/N,kp=54%,θc=355 ℃,tan δ=2.6%,which indicates that the ceramics have a promising application in many fields.