Structural characterization of epitaxial LiFe5O8 thin films grown by chemical vapor deposition

• Atomic ordering in LiFe5O8 bulk single crystal and epitaxial thin films.
• Electron diffraction studies reveal different level of ordering in the system.
• Formation of γ-Fe2O3 like phase has been observed.

We report on detailed microstructural and atomic ordering characterization by transmission electron microscopy in epitaxial LiFe5O8 (LFO) thin films grown by chemical vapor deposition (CVD) on MgO (001) substrates. The experimental results of LFO thin films are compared with those for bulk LFO single crystal. Electron diffraction studies indicate weak long-range ordering in LFO (α-phase) thin films in comparison to bulk crystal where strong ordering is observed in optimally annealed samples. The degree of long-range ordering depends on the growth conditions and the thickness of the film. Annealing experiment along with diffraction study confirms the formation of α-Fe2O3 phase in some regions of the films. This suggests that under certain growth conditions γ-Fe2O3-like phase forms in some pockets in the as-grown LFO thin films that then convert to α-Fe2O3 on annealing.