Gas sensing and conductivity relationship on nanoporous thin films: A CaCu₃Ti₄O₁₂ case study

In this work, CaCu₃Ti₄O₁₂ (CCTO) thin films were synthesized with the polymeric precursor method and characterized by structural (X-ray diffraction) and morphological (scanning electron microscopy) techniques. These films were composed of a single CCTO phase and presented high surface porosity. The gas sensing response and conductivity-type relationship were investigated by two different approaches. Gas sensing measurements performed at different temperatures using different atmospheres showed that the CCTO has n-type gas sensing behavior and can detect small amounts of oxidizing gases with high sensitivity and selectivity. The type of intrinsic conductivity was also investigated through thermopower measurements, which indicated intrinsic n-type conductivity in CCTO thin films prepared with the polymeric precursor method and confirmed the direct relationship between the gas sensing behavior and the intrinsic conductivity of CCTO. - Highlights: • Nanoporous gas sensing CaCu₃Ti₄O₁₂ thin films • CaCu₃Ti₄O₁₂ thin films are prepared with the polymeric precursor method • Films exhibited n-type gas sensing behavior and high sensitivity to oxidizing gases. • Gas sensing and conductivity relationship is established.