Enhanced dielectric and piezoelectric properties in Li/Sb-modified (Na, K)NbO3 ceramics by optimizing sintering temperature

In this paper, lead-free (Na0.474K0.474Li0.052)(Nb0.948Sb0.052)O3 ceramics were synthesized by a conventional solid-state reaction route. The effects of sintering temperature on the crystal structure, microstructure, densification, dielectric properties, and ferroelectric properties of the KNNLS ceramics were addressed. X-ray diffraction patterns and Raman spectrum indicated a transition from orthorhombic to tetragonal phase during the sintering temperature region. This transition is attributed to the migration of Li between the matrix grain and grain boundary. Scanning electron microscopy study revealed increased grain size and enhanced densification with increasing sintering temperature. The density of the ceramics sintered at 1080 °C reached a maximum value of 4.22 g/cm3. KNNLS ceramics sintered at an optimum temperature of 1080 °C exhibited high piezoelectric properties, that is 242 pC/N for d33, 0.42 for kp and 18.2 μC/cm2 for Pr.