Nonlinear Analysis and In-Situ Ferroelectric Characterizations for (K0.49 Na0.49li0.02) (Nb0.98sb0.02)O3 Lead Free Ceramic

The solid-state sintering technique has been implemented to synthesize (K 0.5 Na 0.5 NbO 3 )-0.02(LiSbO 3 ) (KNN-LS) Pb-free ceramic. The crystal structure, dielectric properties and ferroelectric properties below and above the domain switching have been investigated. Pure orthorhombic perovskite phase (I220/I002 = 1.68) with Amm2 space group has been detected at room temperature for sintered ceramic eximined by XRD. Two anomalous permittivity peaks corresponding to (O-T) phase transition at T=175 o C and (T-C) phase transition at T=355 o C have been observed. Rayleigh model was applied below and above the polymorphic phase transition (PPT) temperature in sub-switching region of domain. The model shown that the maximum extrinsic contributions attributed to domain wall motion and domain grow effect was observed at 175 o C, while the intrinsic peak caused by lattice distortion and domain wall propagation was achieved at 200 o C. The co-existence of extrinsic and intrinsic contributions was detected at 175 o C which could be responsible for increasing the permittivity value at PPT point. Reducing the dielectric response above PPT point is back to increase the lattice symmetry in tetragonal phase and clamping effect at high temperature. In-situ ferroelectric properties of KNN-LS ceramic were investigated in a wide range of temperatures (RT-225) ° C. The results shown both of remnant polarization and coercive field were decreased by increasing temperature and the lowest values were achieved at 150 [[EQUATION]] C. Due to increase the domain switchability at higher temperatures in addition increase the leakage current and dielectric loss at high temperature Inverse behavior was observed above 150°C. The present results are interested for understanding the mechanism of highest permittivity value of KNN doped LS ions at PPT point.