Structure and electric properties of NaxLa(2−x)/3Cu3Ti4O12 ceramics prepared by sol–gel method

Abstract

The NaxLa(2−x)/3Cu3Ti4O12 (x = 0.50, 0.35, 0.20, 0.05) ceramics were designed on the premise of charge balance and were prepared by the sol–gel method. The phase structure, microstructure, electric properties of the NaxLa(2−x)/3Cu3Ti4O12 (x = 0.50, 0.35, 0.20, 0.05) ceramics were investigated. The results indicated that with the decreasing of x, the NaxLa(2−x)/3Cu3Ti4O12 (x = 0.50, 0.35, 0.20, 0.05) ceramics showed different microstructure and electrical behaviors. When x = 0.35, the NaxLa(2−x)/3Cu3Ti4O12 ceramics showed the biggest dielectric constant, but still kept the lower dielectric losses. When x = 0.20 and 0.05, the dielectric losses of NaxLa(2−x)/3Cu3Ti4O12 (x = 0.20, 0.05) ceramics were decreased, which were consistent with the primary aim of the present study. However, the dielectric constant of NaxLa(2−x)/3Cu3Ti4O12 (x = 0.20, 0.05) ceramics also were decreased, which was an unwanted result. In addition, with the decreasing of x, the second step-like increases and small peaks (A2) in the curses of dielectric constant-temperature, and the second relaxation peaks (a2) in the electric modulus analysis gradually weaken and finally disappeared. The conduction characteristics of NaxLa(2−x)/3Cu3Ti4O12 (x = 0.50, 0.35, 0.20, 0.05) ceramics had changed from two linear area to a linear area. Interestingly, when x = 0.35, the second relaxation energy values of NaxLa(2−x)/3Cu3Ti4O12 were relatively small and even much smaller than the first relaxation activation energy values, and the first relaxation activation energy value and second relaxation activation energy value were less than 0.70 eV, which might be attributed to the same role of the first ionization of oxygen vacancies, which were different from other ceramics. From the above the results of research, on the premise of charge balance, with change of Na+ and La3+ content, different the microstructure and electrical behavior of NaxLa(2−x)/3Cu3Ti4O12 ceramics might be due to the different defect structure.