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Title: The local environment of cobalt in amorphous, polycrystalline and epitaxial anatase TiO{sub 2}:Co films produced by cobalt ion implantation

Amorphous, polycrystalline anatase and epitaxial anatase TiO{sub 2} films have been implanted with 5 at. % Co{sup +}. The magnetic and structural properties of different microstructures of TiO{sub 2}:Co, along with the local coordination of the implanted Co atoms within the host lattice are investigated. In amorphous TiO{sub 2}:Co film, Co atoms are in the (II) oxidation state with a complex coordination and exhibit a paramagnetic response. However, for the TiO{sub 2}:Co epitaxial and polycrystalline anatase films, Co atoms have a distorted octahedral (II) oxygen coordination assigned to a substitutional environment with traces of metallic Co clusters, which gives a rise to a superparamagnetic behavior. Despite the incorporation of the implanted atoms into the host lattice, high temperature ferromagnetism is absent in the films. On the other hand, it is found that the concentration and size of the implantation-induced nanoclusters and the magnetic properties of TiO{sub 2}:Co films have a strong dependency on the initial microstructure of TiO{sub 2}. Consequently, metallic nanocluster formation within ion implantation prepared transition metal doped TiO{sub 2} can be suppressed by tuning the film microstructure.
Authors:
 [1] ;  [2] ; ; ;  [1] ; ; ; ;  [3] ;  [1] ;  [4]
  1. Helmholtz-Zentrum Dresden - Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstr. 400, 01328 Dresden (Germany)
  2. (Germany)
  3. Lomonosov Moscow State University (MSU), Faculty of Physics, 119991 Moscow (Russian Federation)
  4. (France)
Publication Date:
OSTI Identifier:
22410173
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 18; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COBALT; COBALT IONS; CONCENTRATION RATIO; DOPED MATERIALS; EPITAXY; FERROMAGNETISM; FILMS; MAGNETIC PROPERTIES; MICROSTRUCTURE; NANOSTRUCTURES; PARAMAGNETISM; POLYCRYSTALS; SUPERPARAMAGNETISM; TITANIUM OXIDES; VALENCE