Enhanced electrical properties of the polymorphic phase boundary on the tetragonal side in K0.48Na0.52NbO3-based lead-free piezoelectric ceramics

Herein, (0.95-x)K0.48Na0.52NbO3-0.05SrTiO(3)-xCaZrO(3) piezoelectric ceramics were prepared using a conventional solid sintering process, and their microstructures, phase structures, and ferroelectric, dielectric, and strain properties were studied. The crystal structure of the ceramics changed from the coexistence of an orthogonal-tetragonal phase on the orthogonal side at x = 0 to that on the tetragonal side at x = 0.02 by improving the orthogonal-tetragonal transition temperature (similar to 20 degrees C) with increasing CaZrO3 (abbreviated as CZ) doping. A high electric field-induced strain of 0.33% with a Curie temperature of T-c = 256 degrees C was obtained at x = 0.02 and was approximately two times that observed at x = 0. The dielectric constant and maximum polarization were the highest at x = 0.02 in this (0.95-x)K0.48Na0.52NbO3-0.05SrTiO(3)-xCaZrO(3) system. These materials would be promising lead-free ceramics in the future.

Automated summary

In this study, (0.95-x)K0.48Na0.52NbO3-0.05SrTiO(3)-xCaZrO(3) piezoelectric ceramics were prepared and their microstructures, phase structures, and ferroelectric, dielectric, and strain properties were investigated. The crystal structure of the ceramics changed from orthogonal-tetragonal coexistence to tetragonal-orthogonal coexistence by improving the transition temperature with increasing CaZrO3 doping. These materials exhibited a high electric field-induced strain and excellent ferroelectric and dielectric properties, making them promising candidates for lead-free ceramics in the future.