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| Batista,Marcelo Augusto; Costa,Antonio Carlos Saraiva da; Bigham,Jerry Marshal; Paesano Junior,Andrea; Berndt,Graciele; Inoue,Tadeu Takeyoshi; Nonaka,Adriele Galeti. |
| Synthetic aluminum-substituted maghemites were characterized by total chemical analysis, powder X-ray diffraction (XRD), Mössbauer spectroscopy (ME), and vibrating sample magnetometry (VSM). The aim was to determine the structural, magnetic, and hyperfine properties of γ-Fe2-xAl xO3 as the Al concentration is varied. The XRD results of the synthetic products were indexed exclusively as maghemite. Increasing Al for Fe substitution decreased the mean crystalline dimension and shifted all diffraction peaks to higher º2θ angles. The a0 dimension of the cubic unit cell decreased with increasing Al according to the equation a o = 0.8385 - 3.63 x 10-5 Al (R²= 0.94). Most Mössbauer spectra were composed of one sextet, but at the highest substitution rate of 142.5... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Isomorphous substitution; Hyperfine parameters; Spinel; Ferromagnetic. |
| Ano: 2013 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832013000600013 |
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| Batista,Marcelo Augusto; Costa,Antonio Carlos Saraiva da; Souza Junior,Ivan Granemann de; Bigham,Jerry Marshal. |
| Maghemite (g-Fe2O3) is the most usually found ferrimagnetic oxide in red basalt-derived soils. The variable degrees of ionic substitution of Fe3+ for different metals (e.g. Ti4+, Al3+, Mg2+, Zn2+, and Mn2+) and non-metals in the maghemite structure influence some cristallochemical features of this iron oxide. In this study, synthetic Zn-substituted maghemites were prepared by co-precipitation in alkaline aqueous media of FeSO4.7H2O with increasing amounts of ZnSO4.7H2O to obtain the following sequence of Fe3+ for Zn2+ substitutions: 0.0, 0.025, 0.05, 0.10, 0.15, 0.20, and 0.30 mol mol-1. The objective of this work was to evaluate the cristallochemical alterations of synthetic Zn-substituted maghemites. The dark black synthetic precipitated material was... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Iron oxides; X ray diffraction; Mass-specific magnetic susceptibility; Specific surface area; Isomorphic substitution. |
| Ano: 2008 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832008000200011 |
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