Electrochemical modification of La₂CuO₄: The role played by microstructure

Using electrochemical oxidation as a probe technique for the mechanisms by which oxidation occurs in c-axis La2CuO4 films, the vital role played by specific through-film microstructural defects has been observed using transmission electron microscopy. These defects are namely the large through-film precipitates sometimes found in these films and {111} planar faults. Two high-oxygen-content phases are formed; one locally and with a superstructure, the other of reduced orthorhombicity and larger c-axis than as-grown material. Some films were found not to oxidize, and the defects in these films were compared with those in the oxidizable films.