Synthesis and characteristics of (Bi2Ba3O4−δ)b1/b2CoO2 thin films by chemical solution deposition

(Bi2Ba3O4−δ)b1/b2CoO2 (BBC) thin films are prepared on LaAlO3 (001) single crystal substrates by chemical solution deposition. The annealing temperature effects on the thin film microstructures as well as transport properties are investigated. The results of X-ray diffraction, energy dispersive spectrometry and transmission electron microscopy confirm the formation of stoichiometric BBC thin films with c-axis orientation. Annealing temperature plays a very important role in determination of resistivity and Seebeck coefficient due to the variations of grain size, carrier concentration and mobility. The resistivity behaviors for the different temperature-annealed thin films obey different electrical transport mechanisms at low, medium and high measured temperature ranges. The optimized BBC thin film is annealed at 600 °C, showing a metal-insulator transition at about 100 K and the resistivity and Seebeck coefficient at 300 K is of 8.7 mΩ cm, 74.4 μV K−1, respectively. The results will provide an effective route to fabricate BBC thin films as well as a guidance for investigation about its transport properties.