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°C in N2 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 ∼3 × 104 at 1 kHz, obtained in the HP sample having a relatively smaller grain size of ∼2.4 m, is assumed to be associated with a higher dielectric constant of thinner grain-boundary phases. The low grain-boundary resistivities of 199–319 kΩ·cm in the HP samples are likely induced by the N2 atmosphere and less Cu-rich grain-boundary phase.
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