Role of Sintering Temperature on the Phase Stability and Electrical Properties of 0.94(K0.5Na0.5NbO3)–0.06(LiSbO3) Ceramics

Abstract

Lead-free 0.94(K0.5Na0.5NbO3)–0.06(LiSbO3) (KNN–LS) ceramics were prepared by conventional solid-state reaction route (CSSR). For single perovskite phase formation the calcination was done at 850 °C for 6 h. Whereas for obtaining dense morphology the sintering of KNN–LS ceramics was carried out at 1060, 1080, 1100, and 1120 °C temperatures for 4 h, respectively. The structural study revealed that with the increase in sintering temperature the structure of the ceramic transformed from pure tetragonal to pseudocubic phase. Scanning electron microscopy (SEM) micrographs indicated that the optimum sintering temperature of the ceramic was found to be 1080 °C. The Curie temperature (Tc) of the KNN–LS ceramic was found to decrease at higher sintering temperature. The development of typical hysteresis loop confirmed the ferroelectric and piezoelectric nature of the KNN–LS ceramics sintered at different temperatures. The KNN–LS ceramics sintered at 1080 °C showed better ferroelectric and piezoelectric properties i.e., remnant polarization (Pr)∼17.2 µC/cm2, coercive field (Ec)∼13.5 kV/cm, piezoelectric coefficient (d33)∼161 pC/N, coupling coefficient (kp)∼0.36 and remnant strain ∼0.06% were obtained.