Ferroelectric Phase Transitions in Aurivillius Structure Lead-Free CaBi_4Ti_4O_(15) and CaBi_(3.6)Nd_(0.4)Ti_4O_(15) Ceramics

摘要

Ferroelectrics with high T_C > 600 K attract much attention due to prospects of their applications at high temperatures. In this work, influence of partial substitutions on the crystal structure and dielectric properties of lead-free bismuth oxides Ca(Bi_(1-x)Nd_x)_4Ti_4O_(15) (x = 0, 0.1) have been studied. Ceramic solid solutions have been prepared by the solid state reactions. Optimal temperatures of synthesis and sintering of the samples were determined. Phase composition, structure and microstructure of the samples were studied using the X-ray diffraction and scanning electron microscopy methods, respectively. Phase transitions and ferroelectric properties were studied by the dielectric spectroscopy. Positive effect of the Mn_2O_3 and Bi_2O_3 additives was proved. They favor to improving density of ceramics, inhibiting grain growth and to decreasing dielectric loss.