Study of Fe-doped TiO2 and SnO2 by Mössbauer spectroscopy and FP-LAPW calculations

A.F. CABRERA; L. ERRICO; A. MUDARRA NAVARRO; C.E. RODRÍGUEZ TORRES; M. RENTERÍA; F.H. SÁNCHEZ; M. WEISSMANN

Rio de Janeiro, Brasil

Congreso; LACAME2006, Latin American Conference on Mossbauer Effects; 2006

CNPB, Rio de Janeiro (Brasil)

During the last years the study of transition metal-doped TiO2 and SnO2semiconductors has become a topic of interest, not only because of the many currentindustrial applications of these materials, as for example in catalysis, but also because oftheir potential use in spintronic devices.There is a great deal of new experimental and theoretical work on these TM-dopedsystems (TM= Mn, Co, Fe, Ni, Cu), focused on their magnetic properties. In the case of Fedoping, Mössbauer studies were performed in order to elucidate the local atomic structuresassociated to the observed interactions [1]. Despite the several reports published onquadrupole splitting data, a unique consensus on the hyperfine parameters associated to Fesubstitutional in the rutile structure has not been achieved yet. Several questions remainopen concerning the Fe dopants location in the host structure, and/or the short range ordersaround impurities, as well as the assignment of the observed hyperfine interactions.In 2002 we demonstrated the capability of the ab initio full potential linearizedaugmented plane waves (FP-LAPW) method to predict the hyperfine parameters atimpurity sites [2]. Following this approach, in this work we present a comparativeMössbauer and FP-LAPW study of the hyperfine parameters at Fe impurity in the rutilephase of TiO2 and SnO2. Samples of TiO2 and SnO2 doped with 7 and 10 at.% of Fe wereprepared by mechanical alloying. The sampkes were characterized by X-ray Diffraction, 57 Fe Mössbauer, and magnetometry measurements. The calculations were performedassuming substitutional and interstitial Fe locations and for different impurit yconcentrations. The effects of oxygen vacancies is also discussed.[1] A. Punnoose et al., Phys, rev. B. 72, 54402 (2005); U.Wdowik and K. Ruenbenbauer,Phys. Rev. B 63, 125101 (2001).[2] L.A.Errico et al., Phys. Rev. Lett. 89, 55503 (2002).