Dopant local structure and magnetic behavior of Fe-doped TiO2 anatase nanoparticles

C. E. RODRÍGUEZ TORRES; A. F. CABRERA; L. A: ERRICO; C. ADAN; F. G: REQUEJO; M. WEISSMANN; S. J. STEWART

LNLS, Campinas, Brasil.

Congreso; XVIII Reunión Anual de Usuarios del LNLS; 2008

LNLS

Trabajo presentado en forma de poster durante la reunion We present an investigation of the local structure of dopant sites and magnetic behavior of Fe-doped TiO2 anatase nanoparticles (2.8 and 5.4 at.% Fe) through x-ray absorption experiments, 57Fe Mössbauer spectroscopy, ab initio calculations and magnetometry. The iron K-edge near-edge and extended x-ray absorption fine structure results indicate that Fe(III) replaces Ti(IV) and causes an enlargement of metal-anion bonds length. Mössbauer spectra recorded at room temperature show asymmetric Fe3+ broad doublets. Structural, hyperfine and magnetic properties were investigated from first-principles calculations using the density-functional approach assuming that iron substitutionally replaces Ti in the anatase lattice. A good agreement between theory and experiment is achieved when anionic vacancies at the iron-oxygen octahedron are taken into account. Mössbauer and magnetic measurements indicate that a fraction of Fe3+ diluted in TiO2 remains paramagnetic down to low temperatures. Further, the emergence of magnetically isolated clusters is favored as the amount of dopant increases.