Effect of the addition of B2O3 and BaO–B2O3–SiO2 glasses on the microstructure and dielectric properties of giant dielectric constant material CaCu3Ti4O12

The effect of the addition of glassy phases on the microstructure and dielectric properties of CaCu3Ti4O12 (CCTO) ceramics was investigated. Both single-component (B2O3) and multi-component (30 wt% BaO–60 wt% B2O3–10 wt% SiO2 (BBS)) glass systems were chosen to study their effect on the density, microstructure and dielectric properties of CCTO. Addition of an optimum amount of B2O3 glass facilitated grain growth and an increase in dielectric constant. However, further increase in the B2O3 content resulted in its segregation at the grain boundaries associated with a reduction in the grain size. In contrast, BBS glass addition resulted in well-faceted grains and increase in the dielectric constant and decrease in the dielectric loss. An internal barrier layer capacitance (IBLC) model was invoked to correlate the dielectric constant with the grain size in these samples.

Scanning electron micrograph of 30 wt% BaO–60 wt% B2O3–10 wt% SiO2 (BBS) glass-added CaCu3Ti4O12 ceramic on sintering.Figure optionsDownload as PowerPoint slide