Diversified electrical properties of (1-x)Ba^sub 0.90^Ca^sub 0.10^Ti^sub 0.95^Zr^sub 0.05^O^sub 3^–(x)RuO^sub 2^ ceramics with defect electron complexes

Lead-free (1-x)Ba0.90Ca0.10Ti0.95Zr0.05O3-(x)RuO2 (x = 0-2.0 mol%) ceramics were prepared by conventional solid state reaction with the as-synthesized nanoparticles by a modified Pechini method, showing high densification (96.4-97.1%) with the grain size of ~2.2 µm. Effects of RuO2 contents on the ceramics crystal structure and electrical properties were investigated. The phase evolution was identified by X-ray powder diffraction analysis, and the coexisted Tetragonal and Rhombohedral phases were detected at x around 1.0 mol%. The formation mechanism of defect electron complexes was sated in detail. Diversified dielectric properties and ferroelectric relaxation stemmed from defect electron complexes, charge accumulation at grain boundary, long-range ferroelectric dipole order, etc. Ferroelectric properties could be optimized apparently by polarized-aged process. The optimum electrical properties, i.e. d33 = 195 pC/N, kp = ~0.22, and Qm = 78.9, were obtained at x = 1.0 mol%.