To evaluate the electrochemical and electronic properties of strained film specimen, La1-xSrxCoO3-δ (x = 0.4, 0.5) films were evaluated by means of electrochemical impedance spectroscopy and electrical conductivity measurement. Dense polycrystalline La1-xSrxCoO3-δ films were fabricated on a polycrystalline Ce0.9Gd0.1O1.95 substrate by a pulsed laser deposition technique. Obtained film was (001) oriented in the pseudo-cubic perovskite unit cell and tensile strained along out-of-plane direction. It was confirmed that oxygen nonstoichiometric behavior of the film was different from that of bulk La1-xSrxCoO3-δ and analyzed by assuming localized and itinerant electronic states. Localized electron model with Co2+, Co3+ and Co4+ shows good agreement with observed oxygen nonstoichiometry of the film. The electrical conductivity of La1-xSrxCoO3-δ films show positive temperature coefficient like semiconductors although that of the bulk La1-xSrxCoO3-δ shows a negative temperature coefficient like metals. This indicates localized electron for the La1-xSrxCoO3-δ film and itinerant electron for the bulk La1-xSrxCoO3-δ. Although detail mechanism of the strain effect is not fully understood, both oxygen nonstoichiometric and electronic conduction behaviors of the film could be explained by assuming localized electronic state. Plausible electronic structure of the film was proposed and compared with that of bulk La1-xSrxCoO3-δ.
|Number of pages||7|
|Publication status||Published - 2014|
- LaSrCoO film
- Oxygen nonstoichiometry
ASJC Scopus subject areas