Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8155428 | Journal of Magnetism and Magnetic Materials | 2016 | 11 Pages |
Abstract
Detailed EPR investigations on as-grown and annealed TiO2 nanoparticles in the anatase and rutile phases were carried out at X-band (9.6 GHz) at 77, 120-300 K and at 236 GHz at 292 K. The analysis of EPR data for as-grown and annealed anatase and rutile samples revealed the presence of several paramagnetic centers: Ti3+, Oâ, adsorbed oxygen (O2â) and oxygen vacancies. On the other hand, in as-grown rutile samples, there were observed EPR lines due to adsorbed oxygen (O2â) and the Fe3+ ions in both Ti4+ substitutional positions, with and without coupling to an oxygen vacancy in the near neighborhood. Anatase nanoparticles were completely converted to rutile phase when annealed at 1000° C, exhibiting EPR spectra similar to those exhibited by the as-grown rutile nanoparticles. The high-frequency (236 GHz) EPR data on anatase and rutile samples, recorded in the region about g=2.0 exhibit resolved EPR lines, due to Oâ and O2â ions enabling determination of their g-values with higher precision, as well as observation of hyperfine sextets due to Mn2+ and Mn4+ ions in anatase.
Related Topics
Physical Sciences and Engineering
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Authors
S.K. Misra, S.I. Andronenko, D. Tipikin, J.H. Freed, V. Somani, Om Prakash,