Effects of cobalt and sintering temperature on electrical properties of Ba_(0.98)Ca_(0.02)Zr_(0.02)Ti_(0.98)O_3 lead-free ceramics

摘要

Lead-free (Ba_(0.98)Ca_(0.02))(Zr_(0.02)Ti_(0.98))O_3-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 (Ba_(0.98)Ca_(0.02)) (Zr_(0.02)Ti_(0.98))O_3 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 ℃. 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 (ε_r = 2,675) and a low dielectric loss (lanδ = 0.90 %) at 1kHZ. Besides these, high remnant polarization (P_r) and low coercive field (E_c) of 11.5 μC/ cm~2, 0.31 kV/cm are also obtained at (Ba_(0.98)Ca_(0.02_) (Zr_(0.02)Ti_(0.98))O_3-0.8 mol%Co lead-free ceramics. Furthermore, greatly enhanced temperature stability of the piezoelectric properties was obtained in the temperature range from 20 to 90 ℃. The above results indicate that BCZT-Co ceramics are promising lead-free materials for practical applications.