Effects of cobalt and sintering temperature on electrical properties of Ba0.98Ca0.02Zr0.02Ti0.98O3 lead-free ceramics

Abstract

Lead-free (Ba0.98Ca0.02)(Zr0.02Ti0.98)O3-xmol% (x = 0–1.6) cobalt ceramics (BCZT-xCo) have been fabricated by the traditional solid-state reaction technique and the effects of Co and sintering temperature on ferroelectric, dielectric and piezoelectric properties of (Ba0.98Ca0.02)(Zr0.02Ti0.98)O3 lead-free ceramics have been studied systematically. The orthorhombic–tetragonal (T O–T) transition shift towards lower temperature with increasing Co addition, while Curie temperature (T c) remained at relatively high value of 107 °C. And the Main piezoelectric parameters are optimized at x = 0.8 mol% with a high piezoelectric coefficient (d 33 = 330 pC/N), a planar mode electromechanical coupling factor (k p = 46.7 %), a high dielectric constant (e r = 2,675) and a low dielectric loss (tanδ = 0.90 %) at 1kHZ. Besides these, high remnant polarization (P r) and low coercive field (E c) of 11.5 μC/cm2, 0.31 kV/cm are also obtained at (Ba0.98Ca0.02)(Zr0.02Ti0.98)O3-0.8 mol%Co lead-free ceramics. Furthermore, greatly enhanced temperature stability of the piezoelectric properties was obtained in the temperature range from 20 to 90 °C. The above results indicate that BCZT-Co ceramics are promising lead-free materials for practical applications.