Microstructure Evolution and Dielectric Characteristics of CaCu3Ti4O12Ceramics with Sn-Substitution

Abstract

The doping effect of Sn on the microstructure evolution and dielectric properties was studied in CaCu₃Ti 4-x Sn x O 12 polycrystals. Samples were produced by a conventional solid-state reaction method. Sintering was carried out at 1115℃ for 2-16 h in air. The dielectric constant and loss were examined at room temperature over a frequency range between 10² and 10 6 Hz. The microstructure was found to evolve into three stages. Addition of SnO₂ led to an increase in density and advanced formation of abnormal grains. The formation of coarse grains with a reduced thickness of the boundary brought about an enhanced dielectric constant and a lower dielectric loss below ~1 kHz. EDS data showed the Cu-rich phase along the grain boundary, which should contribute to the improved dielectric constant according to the internal barrier layer capacitor model. After all, SnO₂ was an effective dopant to elevate the dielectric characteristics of CaCu₃Ti 4-x Sn x O 12 polycrystals as a promoter for abnormal grain growth.