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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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| Chaves,Lucia Helena Garófalo; Curry,Joan Elizabeth; Stone,David Andrew; Chorover,Jon. |
| In order to investigate the efficiency of sulfate green rust (GR2) to remove Ni from solution, GR2 samples were synthesized under controlled laboratory conditions. Some GR2 samples were synthesized from Fe(II) and Fe(III) sulfate salts by precipitation. Other samples were prepared by coprecipitation, of Ni(II), Fe(II) and Fe(III) sulfate salts, i.e., in the presence of Ni. In another sample, Ni(II) sulfate salt was added to pre-formed GR2. After an initial X-ray diffraction (XRD) characterization all samples were exposed to ambient air in order to understand the role of Ni in the transformation of the GR2 samples. XRD was repeated after 45 days. The results showed that Nious GR2 prepared by coprecipitation is isomorphous to Ni-free GR2, i.e. Ni is... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Nickel incorporation; Nickel adsorption; X-ray diffraction; Isomorphous substitution. |
| Ano: 2007 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832007000400021 |
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