Phase evolution and enhanced electrical properties of (Ba_(0.85)Ca_(0.15-x)Y_x)(Zr_(0.1)Ti_(0.9))O_3 lead-free ceramics

摘要

(Ba_(0.85)Ca_(0.15-x)Y_x)(Zr_(0.1)Ti_(0.9))O_3 (x = 0.00,0.01, 0.02, 0.03 and 0.04) lead-free ceramics with excellent performance were fabricated using a solid-state reaction method. The effects of Y_2O_3 substitution on the crystal structure and electrical properties were investigated in detail. On the basis of the X-ray diffraction, it was clear that Y_2O_3 additive induced phase transition from orthorhombic phase to the coexistence of orthorhombic and tetragonal phases, and then to single tetragonal phase at room temperature with increasing x. Dielectric measurements revealed that a gradual change presented from typical ferroelectric behavior in (Ba_(0.85)Ca_(0.15)) (Zr_(0.1)Ti_(0.9))O_3 to dispersive relaxor-like characteristics in substituted samples. In addition, double permittivity peaks were presented in plots of relative permittivity versus temperature (ε_(r-T) ) with the sample of 0.01 ≤ x ≤ 0.04, which could be associated with composition fluctuation on account of the incorporation of Y_2O_3. The enhanced temperature stabilities of ferroelectric and piezoelectric properties were obtained in the temperature range from 20 to 140 ℃. This result was found to be consistent with the change of dielectric properties. Besides, the outstanding electrical properties were obtained (d_(33) = 564 pC/N, k_p = 58 %, strain = 0.09 %, P_r = 8.38 μC/cm~2, ε_r = 3078, and tanδ = 0.03) at x = 0.02 due to the coexistence of orthorhombic and tetragonal phases.