Paramagnetism and clustering in Fe-doped TiO2 nanoparticles

C. RODRÍGUEZ TORRES; S. J. STEWART; C. ADAN; A. F. CABRERA

JOURNAL OF ALLOYS AND COMPOUNDS

ELSEVIER SCIENCE SA

Año: 2010 vol. 495 p. 485 - 487

0925-8388

The magnetic behavior of Fe-doped TiO2 anatase nanoparticles (2.8 and 5.4 at.%) was investigated throughout magnetizations versus applied field measurements between 2 and 300K temperatures. The experimental results were well-fitted by using the Brillouin function, giving rise to a moment per isolated Fe atom of about 5 Bohr magnetons. The thermal evolution of the number of magnetic ions shows that a decrease of ions in paramagnetic state occurs below 50K for the most diluted sample. However for the 5.4 at.% sample the fall even at room temperature is evident. These moments probably order antiferromagnetically viasuperexchange interactions. Taking into account the low concentration of dopant and the high fraction of interacting ions, a correlated substitution of Fe in cation sites of TiO2 structure needs to be considered.