Anomalous redox properties and ultrafast chemical sensing behavior of double perovskite CaBaCo2O5+δ thin films

Perovskite oxide CaBaCo 2 O 5+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 Co 2+ and high oxygen vacancy concentration have a superfast oxygen sensing response from 620 to 970 K.