Effect of different pH values adjusted by ammonia on the dielectric properties of CaCu3Ti4O12 ceramics prepared by a sol-gel method

To investigate the effect of different pH values (pH = 1, 3, 5, 7) of a solution used to prepare CaCu3Ti4O12 (CCTO) ceramics on the microstructure and dielectric properties of the resultant ceramics, the acid regulator in the solutions was replaced with an alkaline regulator, ammonia water, and CCTO ceramics were prepared through a sol-gel method. The data show that the dielectric constants of the as-prepared samples maintained relatively high values in the frequency range from 1 to 10(7) Hz. In addition, the dielectric loss decreased to 0.028 at 10(3) Hz for the sample prepared at pH = 5. Moreover, the results reveal that the grain size, porosity and content of the CuO phase at the grain boundaries of the CCTO ceramics varied with the pH value. Our results indicate that using an alkaline regulator to adjust the pH value of the synthesis solution is an effective method for reducing the dielectric loss of CCTO ceramics. (C) 2018 Elsevier B.V. All rights reserved.