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Nature of the reversible paramagnetism to ferromagnetism state in cobalt-doped titanium dioxide.
- Source :
- Journal of Applied Physics; 5/15/2005, Vol. 97 Issue 10, p10D325-1-10D325-3, 3p, 5 Graphs
- Publication Year :
- 2005
-
Abstract
- We report that Co<subscript>0.1</subscript>Ti<subscript>0.9</subscript>O<subscript>2-δ</subscript> prepared by the sol-gel technique is a paramagnet following the Curie-Weiss law: x =x0<superscript>+C</superscript>/(T+θ) with θ≃5 K. However, hydrogenation at 673 K in H<subscript>2</subscript>/Ar (5%/95%) gas converts a part of the paramagnetic (P) sample to room temperature ferromagnet (RTFM) and reheating the sample at 573 K in air converts it back to a paramagnet completely. This reversible P⇄RTFM transition has been observed for additional cycles by alternately heating in air and H<subscript>2</subscript>/Ar. It is argued that this RTFM is intrinsic and it is due to Co<superscript>2+</superscript>-Co<superscript>2+</superscript> exchange interaction mediated by oxygen holes which are produced by hydrogenation but eliminated by oxidation. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00218979
- Volume :
- 97
- Issue :
- 10
- Database :
- Complementary Index
- Journal :
- Journal of Applied Physics
- Publication Type :
- Academic Journal
- Accession number :
- 100455151
- Full Text :
- https://doi.org/10.1063/1.1854931