Navegando por Autor "Vasquez, A."

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Mössbauer effect study of a pleistocenic Brazilian fossil
(Springer, 1991-11) Araújo, José Humberto de; Kunrath, J. I.; Costa Jr, M. I. da; Vasquez, A.; Alves Jr, C.; Oliveira, L. D. Dantas de
Some preliminary Mössbauer effect results for a pleistocenic bone fossilized by mineralization process are presented. The presence of some iron-sulphur compounds permits to infer a correlation between the oxidation state of iron and the environmental conditions of fossilization
Mössbauer study of spin-glass Fe x Zn1−x F2 system
(Hyperfine Interaction, 1991-11) Araújo, Jose Humberto de; Cunha, Joao Batista Marimon da; Vasquez, A.; Amaral, L.; Moro, J. T.; Montenegro, F. C.; Rezende, S. M.; Coutinho-Filho, Mauricio D.
57Fe Mössbauer effect measurements in the diluted Ising antiferromagnet Fe x Zn1−x F2 withx=0.25 andx=0.57 at temperatures between 4.2 and 55 K, are reported. DC suceptibility measurements show a spin-glass (SG) phase at low temperatures forx≤0.31. Our Mössbauer spectra show a phase transition to a SG state with antiferromagnetic order (AFSG) forx=0.25 and only antiferromagnetic order forx=0.57.

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