Mossbauer study of Sn(Fe)O2 prepared by mechanosyntesis

V. BILOVOL; A.M. MUDARRA NAVARRO; A.F. CABRERA; C.E. RODRÍGUEZ TORRES; F.H. SÁNCHEZ

Foz de Iguazu

Congreso; XIV International conference on Hyperfine interactions & XIII International Symposium on Nuclear Quadrupole Interactions; 2007

One of the main goals in the study of ferromagnetic semiconductors for devices is the synthesis and characterization of semiconductors that exhibit carrier spin polarization at and above room temperature. This kind of materials is of crucial importance in the emergent spintronic field. The most common class of materials that would qualify as ferromagnetic semiconductors are the transition metal doped semiconductor oxides, which are called oxide diluted magnetic semiconductors (O-DMS). It is very important to distinguish between the true ferromagnetic semiconductors from those that present magnetic hysteresis owing to the formation of secondary magnetic phases. Techniques sensitive to local atomic arrangements, like M¨ossbauer spectroscopy (MS), can be applied to this end. In this work we explore a new route for Fe doped-SnO2 fabrication. One benefit of doping with iron is that MS can be used to observe any iron phase present in the sample, including metallic clusters and other magnetic phases. The precursors, SnO2 and -Fe2O3 (10 at. % of Fe), were milled together in the stoichiometric ratio for different times between 30 min and 10 h, in air. The obtained powders were characterized by MS, X- ray diffraction and magnetic measurements. For relatively short milling times (30 min -2 h) unreacted hematite and metallic Fe (approximately 20 %) were detected by MS. For longer milling times only three paramagnetic interactions were observed in the MS spectra. No evidence of metallic clusters or iron oxides was detected by MS indicating a good dilution of Fe in the rutile SnO2. Magnetic measurements showed a ferromagnetic-like contribution. The possible reasons for this contribution will be discussed.