不同烧结工艺对K0.5Na0.5NbO3陶瓷微结构的影响

采用普通烧结方法和热压烧结方法制备了K0.5Na0.5NbO3(KNN)无铅压电陶瓷.着重研究了两种烧结工艺对陶瓷的微观结构、晶粒形貌及致密度的影响.研究结果表明,两种烧结方法制备的陶瓷样品都具有单一的正交钙钛矿结构,与普通烧结工艺相比,利用热压烧结工艺制备的样品呈现较高的相对密度(大于98%)、较小的晶粒尺寸(0.6μm左右)及较低的介电损耗(1 kHz,tanδ≤2.8%).实验中发现对于热压烧结的样品,通过改变后期退火温度,样品的晶粒尺寸,致密度可以有规律地变化.

Effect of Different Sintering Processing on the Microstructure of K0.5Na0.5NbO3 Ceramics

Lead-free K0.5Na0.5NbO3(KNN) piezoelectric ceramics were prepared by conventional solid-state reaction technique and sintered through conventional and hot-pressing sintering process respectively.The effects of sintering method and annealing temperature on the microstructure,morphology and density of KNN ceramics were investigated.The crystallographic structure of KNN ceramic was investigated by X-ray diffraction(XRD) and the fractured microstructures of sintered ceramics were characterized by scanning electronic microscope(SEM).The results show that all specimens exhibit pure perovskite structures.However,compared with the sample prepared with conventional sintering,higher relative density(greater than 98%),smaller grain size(0.6 μm) and lower tanδ(≤2.8%,1 kHz) are obtained in the KNN ceramics sintered through hot-pressure sintering process,meantime various particle sizes and densities of KNN ceramics can be obtained by selecting suitable annealing temperature.