CaracteriazaÃÃo por difraÃÃo de raios-X e espectroscopia MÃssbauer de nanopartÃculas de SnO2 dopadas com ferro / Characterization by X-ray diffraction and MÃssbauer spectroscopy of SnO2 nanoparticles doped with iron

AUTOR(ES)

Thiago Soares Ribeiro

FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

30/11/2010

RESUMO

In this work structural characterization by x-ray diffraction and MÂossbauer spectroscopy of Fe-doped semiconducting oxide SnO2 nanoparticles is reported. The compound under study (Sn1−xFexOy) was prepared by high energy ball milling and proteic sol-gel. The samples prepared by ball milling showed an increase of Fe-doping in the semiconducting matrix as a function of milling time, as well as amounts of undesirable metallic iron impurities from the milling tools. A series of samples with various Fe concentrations were HCl-washed in order to eliminate the impurities. Results obtained from measurements on these samples showed that Fe enters the host matrix randomly replacing Sn in octahedral sites regardless of iron concentration. It was also showed the presence of oxygen deficient iron sites attributed to the stoichiometric unbalance of precursor materials used in the milling process. Samples of nanosized SnO2 were prepared by proteic sol-gel with three calcination temperatures. It was found that average particle sizes are directly proportional to the temperature. Nanostructured Sn90Fe10O2 was also synthesized by proteic sol-gel. Formation of spurious Fe2O3 was found at calcination temperature of 400ÂC. At 300ÂC, on the other hand, monophased Fe-doped SnO2 was achieved. Likewise the milled samples, this sample presented two different octahedral iron sites, although with quadrupole splitting slightly smaller than those for the milled samples indicating a less distorted crystal structure. The significantly smaller relative number of oxygen-deficient sites in the proteic sol-gel sample shows that this compound has a more stoichiometric concentration of Fe, Sn and O than those prepared by ball milling.

ASSUNTO(S)

engenharia de materiais e metalurgica semicondutores magnÃticos diluÃdos moagem mecÃnica diluted megnetic semiconductors proteic sol-gel high energy ball milling ciÃncia dos materiais

Documentos Relacionados

• Estudo da cristalizaÃÃo de nanopartÃculas de NiO por difraÃÃo e absorÃÃo de raios-X
• Estudo da Estrutura Local dos SÃtios de Ferro em Ligas FeCrMo por Espectroscopia MÃssbauer e DifraÃÃo de Raios -X
• Propriedades estruturais de L-arginina.HCl.H2O pura e dopada com Fe usando difraÃÃo de raios-X de N-feixes.
• Analise quantitativa da composição de escorias siderurgicas pelo metodo de espectroscopia e difração de raios-X
• Estruturas magneticas do EuSe por difração magnetica de raios-X