Dielectric and Grain‐Boundary Characteristics of Hot Pressed CaCu ₃ Ti ₄ O ₁₂

Abstract

Effects of hot pressing (HP) on the dielectric and grain‐boundary characteristics of copper titanate (CaCu 3 Ti 4 O 12 or CCTO) materials were studied with the comparison of conventionally prepared samples. HP at 1100°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 ∼3 × 10 4 at 1 kHz, obtained in the HP sample having a relatively smaller grain size of ∼2.4 μm, 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 N 2 atmosphere and less Cu‐rich grain‐boundary phase.