Lead-free 0.95(K0.6Na0.4)NbO3-0.05(Bi0.5Na0.5)ZrO3 ceramic for high temperature dielectric, ferroelectric and piezoelectric applications

Environment-friendly 0.95(K0.6Na0.4)NbO3-0.05(Bi0.5Na0.5)ZrO3(KNN-BNZ) ceramic have been prepared via high energy ball-milling followed by sintering. The effect of sintering temperature on the structural and piezoelectric properties has been studied and optimization of sintering temperature was carried out. X-ray diffraction (XRD) reveals the coexistence of tetragonal and rhombohedral phases for all the samples sintered at different temperatures. The ceramic sample sintered at 1150 degrees C showed high piezoelectric charge coefficient (d(33) = 340 pC/N) with uniform and dense grains. Relaxor type ferroelectric behaviour with Curie phase temperature around 347 degrees C (at 1 kHz) was obtained. Well saturated and fatigue resistant P-E hysteresis loops with a remnant polarization (P-r) of 19.58 mu C/cm(2) and a coercive field (E-c) of 14.24 kV/cm were obtained at room temperature. A high value of pyroelectric coefficient (p similar to 1855.1 mu Cm-2oC-1) was obtained in the temperature range 90-150 degrees C suitable for pyroelectric applications. Further, piezoelectric generator was fabricated using KNN-BNZ ceramic. An open circuit voltage of similar to 6.2 V was generated from the device under periodic compressive force of 2 kgf. Thus, 0.95(K0.6Na0.4) NbO3-0.05(Bi0.5Na0.5)ZrO3 ceramic can serve as promising material for various electromechanical, ferroelectric and pyroelectric based devices. (C) 2019 Elsevier B.V. All rights reserved.