IFLP   13074
INSTITUTO DE FISICA LA PLATA
Unidad Ejecutora - UE
artículos
Título:
Local electronic structure of dopant sites and magnetic behavior of Fe-doped TiO2 anatase nanoparticles: Experiments and ab initio calculations
Autor/es:
C.E. RODRÍGUES-TORRES; A.F. CABRERA; L.A. ERRICO; F. REQUEJO; M. WAISSMAN; S. STEWART
Revista:
JOURNAL OF PHYSICS CONDENSED MATTER
Referencias:
Año: 2008 vol. 20 p. 135210 - 135219
ISSN:
0953-8984
Resumen:
We present an investigation of Fe-doped TiO2 anatase nanoparticles (2.8 and 5.4 at.% Fe) where Fe substitutes Ti atoms without the presence of other phases. In order to characterize these samples we used x-ray absorption experiments, 57Fe M¨ossbauer spectroscopy, ab initio calculations and magnetometry. Results from iron K-edge near-edge and extended x-ray absorption fine structure confirm that Fe3+ replaces Ti4+ in the TiO2 anatase structure increasing the metal-anion bond length. M¨ossbauer spectra recorded at room temperature show asymmetric Fe3+ broad doublets. These results agree with structural, hyperfine and magnetic properties calculated using density-functional theory, if oxygen vacancies are present in the iron–oxygen octahedra. M¨ossbauer and magnetic measurements indicate that samples are paramagnetic at room temperature. At low temperatures, two kind of magnetic species can be distinguished: (i) isolated paramagnetic Fe3+ ions and (ii) antiferromagnetically coupled Fe3+3+ broad doublets. These results agree with structural, hyperfine and magnetic properties calculated using density-functional theory, if oxygen vacancies are present in the iron–oxygen octahedra. These results also show that substitutional Fe in nanosized anatase TiO2 ferromagnetic ordering.