Microstructure and dielectric properties of CaCu3Ti4O12 ceramics with high breakdown field strength prepared via polymer pyrolysis

Although polymer pyrolysis has been proven to be an excellent method for synthesising advanced functional ceramics, a detailed preparation process has rarely been reported. It is well known that the mass ratio of initiator to monomer (x value) and the molar ratio of monomer to cation (y value) are key factors in polymerisation. To introduce these two crucial parameters and obtain high-performance dielectric ceramics with high breakdown field strength, pure CaCu3Ti4O12 (CCTO) ceramic samples with different x values and then with different y values (at x = 0.5%) were prepared via polymer pyrolysis in this study. The effects of x and y on the microstructure and dielectric performance of the CCTO ceramics were systematically investigated. The results show that CCTO ceramics with y = 2.0 simultaneously exhibited high breakdown field strength (8.71 kV/cm), large dielectric constant (14,892), and low dielectric loss (0.030). The results also demonstrate that a moderate amount of initiator can promote complete polymerisation, and that an appropriate monomer is favourable for strengthening ionic bonding between metal ions and carboxylic acid ions in polymer chains. We believe that this work can provide a guide for the synthesis of CCTO-based and other matrix ceramics with excellent dielectric performance using the polymer pyrolysis method.