Results and discussion
Fig.1 shows the XRD patterns of KNN powder
calcined at 900 "C and the ceramics sintered at 1 120
'C. The phase structure in all samples is pure perovskite
phase with typical orthorhombic symmetry and no any
secondary impurity can be certified. Fig.2 shows the
SEM micrograph of fracture surface of KNN ceramics.
The microstructure of the sample sintered at 1 120 'C is
uniform and fine, the grain boundary is clear, their
microstructure is dense, the average grain size is about 5
pm, the fracture surface is mainly intergranular fracture
as shown in Fig.2.