Dielectric, tunability, leakage current, and ferroelectric properties of (K_0.45Na_0.55)_0.95Li_0.05NbO₃ lead free piezoelectric

In the present work, a perovskite structure of (K_0.45Na_0.55)_0.95Li_0.05NbO₃ lead free ceramic (KNNL) was prepared by solid solution technique then it was calcined at 900 °C for 2 h followed by sintering at 1100 °C for 2 h. A single phase of KNNL has been formed and quite regular stripe nano-scale domains with junctions correspond to grain boundaries has been observed by TEM at room temperature. Two phase transitions temperature were clearly observed: orthorhombic–tetragonal (T_O–T = 130 °C) and tetragonal–cubic transition (T_T–C = 380 °C). Un-switching leakage has been observed drastically suppressed in all range of the electric field, however anomalous peak around (~ 2 kV/cm) has been observed in switching leakage which could be attributed to the domain switching. Meanwhile, the mechanism of dielectric tunability was studied and the findings were interpreted by using Johnson's phenomenological. Additionally, the ferroelectric properties have been investigated by hysteresis loop (P–E) and positive up negative down (PUND) methods. The result of the remnant polarization which appraised by PUND is (Q_sw = 1.831 µC/cm²) which owing to the switching charged density. Piezoelectric properties based on d₃₃ were investigated where its piezoelectric coefficient equal 240 pm/V.