CaCu(3-x)FexTi4O(12)(x=0, 0.015, 0.03, 0.045, 0.06) ceramics were synthesized by sol-gel method. The electrical conduction and dielectric measurements show that the doping of a very small amount of Fe(3+) ions greatly reduces the low-frequency dielectric constants and leakage, and enhances grain resistivity. For the doped samples, the appearance of the strong low-frequency peaks in the spectra of dielectric loss confirms that the doping of Fe(3+) ions induces the contact-electrode effect on ceramic surface. These great changes of electrical properties may originate from the reduced amount of oxygen vacancies by doping Fe(3+)
Zhi YangYue ZhangGuang YouKun ZhangRui XiongJing Shi
Ca1-xRbxCu3Ti4O12(x=0, 0.01, 0.02 and 0.03) ceramics were synthesized by the sol-gel method. Doping Rb+ reduces dielectric loss, which reaches minimum when x=0.02. By measuring properties of electrical conduction, larger leakage current density and height of grain-boundary Schottky potential barrier(fB) were found in the doped samples, and fB became maximum when x=0.02. These results are attributed to the increase in the amount of oxygen vacancies and the formation of Cu-rich/Ti-poor grain-boundary layers, and it can be concluded that the dielectric loss in CCTO ceramic can be reduced by manipulating the composition and electrical properties of grain boundary.
