Preparation and characterization of epitaxial Fe2-xTi xO3 solid solution films

Tatsuo Fujii, Hideki Hashimoto, Yusuke Takada, Makoto Nakanishi, Jun Takada

Research output: Contribution to journalArticle

Abstract

Thin films of hematite-ilmenite (α-Fe2O 3-FeTiO3) solid solution series are proposed to be one of the new high-temperature magnetic semiconductors, We have successfully prepared well-crystallized epitaxial Fe2-xTixO3 films with various Ti content, x, between 0.6 and 1.0. The films were epitaxially formed on α-Al2O3(0001) single-crystalline substrates by reactive helicon plasma sputtering technique. The films prepared at lower substrate temperature below 700°C had the R3̄c structure, in which the Fe and Ti ions randomly occupied octahedral interstices. While the films prepared at higher substrate temperature above 700°C had the R3̄ structure, in which the octahedral interstices occupied by the Fe and Ti ions were arranged in an ordered way along the c-axis. Moreover the films prepared at the higher substrate temperature consisted of nearly stoichiometric oxygen concentration. However, with decreasing the substrate temperature the films seemed to have large cation vacancies and Fe2+ ions were gradually oxidized to Fe3+. With decreasing the Ti content from x=1.0 to 0.6, the electric resistivity of the stoichiometric films was sharply decreased from 10 to 0.1 Ωcm because of the formation of mixed valence states between Fe2+ and Fe3+. The stoichiometric films with x=0.6 were ferrimagnetic semiconductors at room temperature when the films had the R̄̄3 structure.

Original languageEnglish
Pages (from-to)87-94
Number of pages8
JournalCeramic Transactions
Volume195
Publication statusPublished - 2006

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Solid solutions
Substrates
Ions
Temperature
Helicons
Ilmenite
Magnetic semiconductors
Electric conductivity
Hematite
Vacancies
Sputtering
Cations
Positive ions
Semiconductor materials
Oxygen
Crystalline materials
Plasmas
Thin films

ASJC Scopus subject areas

  • Ceramics and Composites

Cite this

Preparation and characterization of epitaxial Fe2-xTi xO3 solid solution films. / Fujii, Tatsuo; Hashimoto, Hideki; Takada, Yusuke; Nakanishi, Makoto; Takada, Jun.

In: Ceramic Transactions, Vol. 195, 2006, p. 87-94.

Research output: Contribution to journalArticle

Fujii, Tatsuo ; Hashimoto, Hideki ; Takada, Yusuke ; Nakanishi, Makoto ; Takada, Jun. / Preparation and characterization of epitaxial Fe2-xTi xO3 solid solution films. In: Ceramic Transactions. 2006 ; Vol. 195. pp. 87-94.
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