Temperature dependant structure Fe{sub 3}O{sub 4}(001) surfaces

Conference · Tue Oct 01 04:00:00 EDT 1996

OSTI ID:370138

Anderson, J F; Diebold, U ^[1]

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1. Tulane Univ. New Orleans, LA (United States)

A detailed knowledge of the surface structure and composition of magnetite (Fe{sub 3}O{sub 4}) is desirable for improving its application in the computer storage industry and in catalysis. We report results on a structural investigation using STM (Scanning Tunneling Microscopy), Low Energy Electron Diffraction (LEED), and x-ray photoelectron spectroscopy (XPS). Fe{sub 3}O{sub 4}(001) films of several micron thickness grown on MgO(100) with molecular beam epitaxy have been used, these films are epitaxial and well-ordered. The surfaces of the films are rather smooth on a wide length scale (average height variation of 20 {Angstrom} over 3000 {Angstrom}), and consist of terraces separated by monoatomic steps. Approximately 10 monolayer deep square pits are also present, but no atomically-resolved STM images could be observed for low annealing temperatures. Upon annealing to 550{degrees}C in UHV, a clear c(1x1) LEED pattern is seen. The real-space STM images show two locally different atomic arrangements. The most prominent features are 25 {Angstrom} wide stripes along the (110) direction with an average separation of 30 {Angstrom}. STM shows the stripe orientation to be orthogonal to one another on adjacent terraces. Upon heating to 600{degrees}C, the overall surface morphology changes. The terraces are no longer square and atomically-resolved rows are visible with a separation of 3.5 {Angstrom} along the (100) and (010) directions on adjacent terraces.

• OSTI ID: 370138
• Report Number(s): CONF-960376--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
66 PHYSICS
ANNEALING
ELECTRON DIFFRACTION
HEATING
IRON OXIDES
MAGNETITE
MORPHOLOGY
PHOTOELECTRON SPECTROSCOPY
TEMPERATURE DEPENDENCE
THIN FILMS