Effect of Co^(2+)substitution in B-sites of the perovskite system on the phase formation,microstructure,electrical and magnetic properties of Bi0.5(Na0.68K0.22Li0.10)0.5TiO3 ceramics

摘要

Bi_(0.5)(Na_(0.68)K_(0.22)Li_(0.10))_(0.5)Ti_(1-x)Co_(x)O_(3) lead-free perovskite ceramics(BNKLT-xCo,x=0,0.005,0.010,0.015 and 0.020)were fabricated via the solid-state combustion technique.A small-amount of Co^(2+)ion substitution into Ti-sites led to modification of the phase formation,microstructure,electrical and magnetic properties of BNKLT ceramics.Coexisting rhombohedral and tetragonal phases were observed in all samples using the X-ray diffraction(XRD)technique.The Rietveld refinement revealed that the rhombohedral phase increased from 39%to 88%when x increased from 0 to 0.020.The average grain size increased when x increased.With increasing x,more oxygen vacancies were generated,leading to asymmetry in the bipolar strain(S-E)hysteresis loops.For the composition of x=0.010,a high dielectric constant(ε_(m))of 5384 and a large strain(S_(max))of 0.23%with the normalized strain (d*_(33))of 460 pm·V^(-1) were achieved.The BNKLT-0Co ceramic showed diamagnetic behavior but all of the BNKLT-xCo ceramics exhibited paramagnetic behavior,measured at 50 K.