Dielectric and Grain-Boundary Characteristics of Hot Pressed CaCu₃Ti₄O₁₂

Effects of hot pressing (HP) on the dielectric and grain-boundary characteristics of copper titanate (CaCu3Ti4O12 or CCTO) materials were studied with the comparison of conventionally prepared samples. HP at 1100 degrees C in N-2 atmosphere resulted in uniformly distributed smaller grain sizes and less Cu-rich grain boundaries, without the accompanying secondary CuO phase. The high effective permittivity of similar to 3 x 104 at 1 kHz, obtained in the HP sample having a relatively smaller grain size of similar to 2.4 mu m, is assumed to be associated with a higher dielectric constant of thinner grain-boundary phases. The low grain-boundary resistivities of 199-319 k center dot cm in the HP samples are likely induced by the N-2 atmosphere and less Cu-rich grain-boundary phase.