Autori: Maria Nicoleta Grecu, Serban Constantinescu, Doina Tarabasanu-Mihaila, Daniela Ghica, and Ion Bibicu

Editorial: Phys. Status Solidi B 248, 12, p.2927–, 2011.

Rezumat:

In this paper we present electron paramagnetic resonance (EPR)
and Mossbauer (transmission method, TMS and measurements
in the scattering method, CEMS) experiments on 57Fe (0.1–
1 at.%) doped nanocrystalline anatase-type TiO2, synthesized
by a hydrothermal method. Different Fe3+ and Fe2+ ions
positions, with various hyperfine interactions evidenced in
Mossbauer spectra (MS), confirm a partial magnetic ordering at
room temperature. The magnetic hyperfine fields in the TMS spectra, better resolved at lower temperatures, do not change
essentially with temperature. The first CEMS measurements,
carried out on iron-doped TiO2 nanoparticles, reveal a larger
disorder in the surface particles layer. The temperature
dependence of the double integral EPR spectral intensity,
proportional with the sample susceptibility, shows an anomalous
behaviour. It suggests the bound magnetic polaron (BMP)
mechanism for the magnetic ordering.

Cuvinte cheie: nanoparticule de anatase, RES,polaroni magnetici, spectroscoopie Mossbauer // anatase nanoparticles, EPR, magnetic polarons, Mossbauer spectroscopy

URL: http://www.pss-b.com