Phase structure of Li _0.058(Na _0.51K _0.49) _0.942NbO ₃ lead-free piezoelectric ceramics

Several kinds of phase structure change behavior in Li _0.058(Na _0.51K _0.49) _0.942NbO ₃ (KNNLN) ceramics were presented in this work. XPS measurement was employed to determine Na volatilization in the KNNLN samples, and this result explains the difference of the phase structure between the surface and interior of the samples. The phase structure of lead-free KNNLN piezoceramics are studied based on the measurements of the analysis of X-ray diffraction pattern and dielectric properties. The poled samples exhibit orthorhombic structure whereas the surface and interior for unpoled samples exhibit tetragonal and tetragonal-orthorhombic coexistent structures, respectively. An explanation to the mechanism of the structure transformation during poling processing was proposed.