BAJAS TEMPERATURAS

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https://nuclea.cnea.gob.ar/handle/20.500.12553/5229

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Examinando BAJAS TEMPERATURAS por Materia "ANALISIS TERMICO"

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  • Miniatura
    ÍtemAcceso Abierto
    Crystal structure refinement, spectroscopic study and magnetic properties of yttrium hexacyanoferrate (III)
    (Elsevier, 2011-09-28) Gil, D.M.; Navarro, M.C.; Lagarrigue, M.C.; Guimpel, J.; Carbonio, R.E.; Gómez, M.I.; Gerencia Física. Departamento Materia Condensada. División Bajas Temperaturas
    Y[Fe(CN)6]·4H2O has been synthesized and characterized. The crystal structure was refined by Rietveld analysis using X-ray powder diffraction data. Y[Fe(CN)6]·4H2O crystallizes in the orthorhombic crystal system, space group Cmcm. Y3+ ion is eight-coordinated forming a bicapped distorted trigonal prism YN6O2. Fe3+ ion is six-coordinated in the form of an irregular octahedra FeC6 group and cyanide linkages between YN6O2 and FeC6 groups build an infinite polymeric array. The vibrational spectrum shows two bands corresponding to antisymmetric and symmetric stretching 12C14N in the CN stretching region. These bands are accompanied by four weak isotopic bands at lower frequency due to the presence of 13C and 15N in relative natural abundance. The HOH bending band split into three bands around 1600 cm−1 due to the presence of two kinds of water molecules in the structure. The thermal decomposition has been followed by thermogravimetric and differential thermal analysis, IR spectroscopy and powder XRD. The size and morphology of the complex and its thermal decomposition products were evaluated by scanning electron microscopy. The magnetic measurements confirm that Y[Fe(CN)6]·4H2O shows an antiferromagnetic order at low temperatures.
  • Miniatura
    ÍtemAcceso Abierto
    Y[Fe1-xCox(CN)6]·4H2O (0 ⩽ x ⩽ 1) solid solutions: Synthesis, crystal structure, thermal decomposition and spectroscopic and magnetic properties
    (Elsevier, 2012-05-16) Gil, D.M.; Guimpel, J.; Paesano Jr., A.; Carbonio, R.E.; Gómez, M.I.; Gerencia Física. Departamento Materia Condensada. División Bajas Temperaturas
    The series of solid solutions Y[Fe1−xCox(CN)6]·4H2O (0 ⩽ x ⩽ 1) were prepared and characterized by means of powder X-ray diffraction (PXRD), Infrared and Mössbauer spectroscopy and magnetic measurements. The thermal decomposition process has been followed by thermogravimetric and differential thermal analysis (TGA–DTA). The crystal structure of the complexes was refined by means of Rietveld analysis. The Y[Fe1−xCox(CN)6]·4H2O complexes crystallize in the orthorhombic crystal system, space group Cmcm. The Y3+ ion is eight-coordinated forming a bicapped distorted trigonal prism YN6O2. The Fe3+ and Co3+ ions are six-coordinated in the form of an irregular octahedra (Fe,Co)C6 group and cyanide linkages between YN6O2 and (Fe,Co)C6 groups build an infinite polymeric array. The Mössbauer spectra of all solid solutions Y[Fe1−xCox(CN)6]·4H2O present quadrupolar splittings with negative isomer shifts values due to the existence of a strong π back-bonding effect from the Fe3+ ion towards the CN ligands. All compounds follow the Curie–Weiss law showing anti-ferromagnetic interactions at very low temperatures.