Coherent Growth of a-Fe2O3 in Ti and Nd Co-doped BiFeO3 Thin Films

Coherent dendritic α-Fe2O3 precipitates were observed to form at the surface of epitaxial films of (Bi0.75Nd0.25)(Fe0.97Ti0.03)O3 (BNFO) grown by pulsed laser deposition. The Fe2O3 dendrites are assemblages of nanosized particles with an approximate length of 500 nm. Through the use of atomic resolution scanning transmission electron microscopy, a transition zone at the BNFO/α- Fe2O3 interface, ∼ 2 unit-cells wide, was observed to be Fe2O3-rich with the perovskite structure. It is proposed that the formation of the Fe2O3-rich perovskite structure encourages epitaxial growth of the α-Fe2O3 rather than the formation of the incoherent Fe2O3 particulate second phase frequently reported in BiFeO3-based thin films.