In:
The Journal of Chemical Physics, AIP Publishing, Vol. 152, No. 5 ( 2020-02-07)
Abstract:
We studied magnetite–hematite–magnetite transformations in an ultrathin epitaxial film on Pt(111) using surface sensitive and bulk sensitive methods. At initial oxidation stages at elevated temperature (810 K), a 5-nm thick magnetite Fe3O4(111) film became non-stoichiometric toward maghemite and then showed the first signs of hematite phase formation under an oxygen exposure of 3 × 103 L. Finally, under 2 × 104 L, the film fully transformed to hematite α-Fe2O3(0001), maintaining a high single-crystal quality. A comparison of the conversion electron Mössbauer spectra and low energy electron diffraction pattern showed that at intermediate oxidation stages, hematite dominated at the surface, whereas a spinel phase was still observed in the deeper layers. The magnetite–hematite conversion was fully reversed by annealing under ultra-high vacuum at temperatures exceeding 600 K, and despite a change in morphology, the magnetite film preserved the original crystal structure and orientation.
Type of Medium:
Online Resource
ISSN:
0021-9606
,
1089-7690
Language:
English
Publisher:
AIP Publishing
Publication Date:
2020
detail.hit.zdb_id:
3113-6
detail.hit.zdb_id:
1473050-9
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