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Nonstoichiometry of Epitaxial FeTiO3+δ Films

Published online by Cambridge University Press:  10 February 2011

Tatsuo Fujii
Affiliation:
Department of Applied Chemistry, Okayama University, Okayama 700–8530, Japan
Makoto Sadai
Affiliation:
Department of Applied Chemistry, Okayama University, Okayama 700–8530, Japan
Masakazu Kayano
Affiliation:
Department of Applied Chemistry, Okayama University, Okayama 700–8530, Japan
Makoto Nakanishi
Affiliation:
Department of Applied Chemistry, Okayama University, Okayama 700–8530, Japan
Jun Takada
Affiliation:
Department of Applied Chemistry, Okayama University, Okayama 700–8530, Japan
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Abstract

Epitaxial thin films of (001)-oriented FeTiO3+δ were prepared on α-Al2O3(001) single crystalline substrates by helicon plasma sputtering technique. The FeTiO3+δ films had large oxygen nonstoichiometry, which seriously depended on both substrate temperature and oxygen pressure during the sputtering deposition. The valence states of Fe ions in FeTiO3+δ changed monotonically from Fe2+ to Fe3+ with decreasing the substrate temperature from 900 to 400°C or with increasing the oxygen pressure from 0.9 to 1.8×10-6 Pa. The change of Fe valence states from Fe2+ to Fe3+ induced the magnetic phase transition only for the films prepared at 900°C. The films containing Fe2+ were paramagnetic while those with Fe3+ were antiferromagnetic at room temperature. The oxygen nonstoichiometry of the FeTiO3+δ films was probably produced by cation vacancies and disarrangement of Fe3+ and Ti4+ ions, which randomly occupied both interstitial and substitutional sites of the FeTiO3 related structure.

Type
Research Article
Copyright
Copyright © Materials Research Society 2003

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References

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