Influence of sintering temperature on the structure and piezoelectric properties of ZnO-modified (Li, Na, K)NbO₃ lead-free ceramics

Abstract

ZnO-modified (Li, Na, K)NbO₃ lead-free ceramics with a nominal composition of Li_0.06(Na_0.535K_0.48)_0.94NbO₃+0.7mol% ZnO (LNKN-Z₇) was synthesized normally at 930–1000°C. The Zn ions incorporated into the A-site at a higher sintering temperature, which changed LNKN-Z₇ to soft piezoelectric ceramics with the mechanical quality factor decreasing from 228 to 192. A phase transition from tetragonal to orthorhombic symmetry was identified by XRD analysis, and the corresponding calculation of lattice parameters was conducted at 970–980°C. Because of such transitional behavior and fine microstructure, the optimized values of piezoelectric coefficient, planar electromechanical coupling coefficient, and relative dielectric constant were obtained.

Keywords

piezoceramics / niobates / zinc oxide / modification / phase transitions / piezoelectricity / sintering

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