Dielectric characterization of polycrystalline and epitaxial thin-film CaCu3Ti4O12 (CCTO)

High dielectric CaCu₃Ti₄O₁₂ (CCTO) thin films were successfully grown on SrRuO₃ (SRO) conductive films on LaAlO₃ (LAO) substrates by the Pulsed Laser Deposition (PLD) method. Both the Dielectric properties of the [001] oriented epitaxial thin-film and the polycrystalline CCTO were evaluated. The general feature of the dielectric responses of the [001] epitaxial thin film and the polycrystalline CCTO are similar. That is, both can be modeled by the series combination of two parallel R-C circuits. While the gigantic relaxation process observed in polycrystalline CCTO is accounted for by the interaction between the grain volume resistance and grain boundary capacitance, the gigantic relaxation process in the [001] oriented epitaxial thin-film CCTO is proposed to be caused by the mutual interaction of the domain volume resistance and the domain boundary capacitance. Domain boundaries are likely to be at twin boundaries within the [001] oriented epitaxial thin-film CCTO.