Environment friendly novel piezoelectric 0.94[Na0.8K0.2NbO3]–0.06LiNbO3 ternary ceramic for high temperature dielectric and ferroelectric applications

A new composition of lead free piezoelectric ternary ceramic 0.94[Na0.8K0.2NbO3]–0.06LiNbO3 has been synthesized. A well defined and less porous microstructure of the ceramic was prepared by optimized sintering at 1155 °C. High temperature orthorhombic to tetragonal phase transitions at 194 °C and Curie phase transition at 438 °C were observed with real dielectric constant values ∼1400 and 10,500 at 1 kHz, respectively. The NKLN ceramic showed normal ferroelectric behavior. Its ac conductivity followed jump relaxation model for lower frequencies and double power law at higher frequencies with strong temperature dependence. A very high value of the piezoelectric charge coefficient 291 pC N−1 was obtained which implies its potential application in piezoelectric devices. Well switchable square shape and fatigue free P–E loops with high remnant polarizations were obtained in the temperature range 20 °C–100 °C. Pyroelectric coefficient value was found to be −874.3 μC m−2 °C−1 and 560 μC m−2 °C−1 for the temperature range 20 °C–60 °C and 60 °C– 100 °C respectively.