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Perovskite oxide CaBaCo2O5+δ (CBCO) thin films with two divalent alkaline earth metal ions and the transition metal Co ion were prepared by pulsed laser deposition (PLD) system. X-ray diffraction reveals that the as-grown CBCO thin films have good crystallinity of the perovskite structure. Redox electrical properties and chemical sensing behavior on the as-grown CBCO thin films were systematically studied under various chemical environments. The electrical transport property studies indicate that the electrical resistivity increases with increase of temperature under reducing atmosphere and the temperature dependence of resistivity of the CBCO thin film in the oxidation processing above room temperature can be well fitted by small polaron hopping model. The chemical sensing property measurements reveal that the CBCO thin film is very sensitive to oxidizing/reducing environments in the temperature ranges from 620 K to 970 K. Especially, the reduced CBCO thin films with Co2+ and high oxygen vacancy concentration have a superfast oxygen sensing response from 620 to 970 K.

Perovskite cobaltates LaBaCo 2 O 5.5+ δ thin films were directly integrated onto (001) Si substrates by pulsed laser deposition. Microstructural studies from X-ray diffraction reveal that the LaBaCo 2 O 5.5+ δ films are polycrystalline. Electrical transport property measurements indicate that the polycrystalline LaBaCo 2 O 5.5+ δ films have a semiconductor behavior with a largest magnetoresistance value of 18% at ~40 K. Magnetization property measurements show that the polycrystalline films exhibit magnetic behavior similar to its bulk materials of nanoscale ordered LaBaCo 2 O 6 and have larger magnetic moments and magnetic coercive field than the single-crystal LaBaCo 2 O 5.5+ δ films.