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- Author or Editor: C. Guerreiro x
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Abstract
The influence of additions of 2, 4, 6, 8, 10 and 12 mass% Ag on the thermal behavior of the Cu–8 mass% Al alloy was studied using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffractometry (XRD). The results indicate that the presence of silver introduces new thermal events, due to the formation of a silver-rich phase and, for additions of 10 and 12 mass% Ag, it is possible to verify the formation of the γ1 phase (Cu9Al4) and the metastable transitions which are only observed in alloys with a minimum of 9 mass% Al.
Abstract
Metal complexes of calcium with 5,7-dibromo, 7-iodo and 5-chloro-7-iodo-8-hydroxyquinolate were precipitated in aqueous ammonia and acetone medium, except for the solid state compound with 5,7-dichloro-8-hydroxyquinoline which hasn"t been obtained under these conditions. The complexes obtained through the mentioned precipitation are Ca[(C9H4ONBr2)2]3H2O, Ca[(C9H5ONI)2]2H2O and Ca[(C9H4ONICl)2]2.5H2O. Their intermediate from the thermal decomposition found through TG/DTA curves in air indicated the presence of different kinds of calcium carbonates related to the reversibility and crystalline structure, depending on the original compounds. The initial compounds and the intermediate from the thermal decomposition were also characterized through IR spectra and X-ray diffraction.
Abstract
Magnesium ion was reacted with 5,7-dibromo-, 5,7-dichloro-, 7-iodo-and 5-chloro-7-iodo-8-hydroxyquinoline, in acetone/ammonium hydroxide medium under constant stirring to obtain (I) Mg[(C9H4ONBr2)2]2H2O; (II) Mg[(C9H4ONCl2)2]3H2O; (III) Mg[(C9H5ONI)2]2H2O and (IV)Mg[(C9H4ONICl)2]2.5H2O complexes. The compounds were characterized by elemental analysis, IR spectra, ICP, TG-DTA and DSC. Through thermal decomposition residues were obtained and characterized, by X-ray diffractometry, as a mixture of hexagonal MgBr2 and cubic MgO to the (I) compound at 850C; cubic MgO to the (II), (III) and (IV) compounds at750, 800 and 700C, respectively.
Abstract
Strontium complexes of 5,7-dibromo-, 5,7-dichloro-, 7-iodo- and 5-chloro-7-iodo-8-hydroxyquinoline were precipitated from an aqueous ammonia and acetone medium. The complexes obtained were Sr[(C9H4ONBr2)2]2.5H2O; Sr[(C9H4ONCl2)(OH)]1.5H2O; Sr[(C9H5ONI)2]5H2O and Sr[(C9H4ONICl)(OH)]1.25H2O. The residues of their thermal decomposition were SrBr2; a mixture of SrCl2, SrCO3 and SrO; SrCO3 and SrCO3, respectively. All were characterized by means of thermogravimetry, differential thermal analysis, complexometry with EDTA, atomic absorption spectroscopy, IR spectroscopy and X-ray diffraction.
Abstract
In this present work, barium ion was reacted with different ligands which are 5,7-dibromo 5,7-dichloro, 7-iodo and 5-chloro-7-iodo-8-hydroxyquinoline, in acetone/ammonium hydroxide medium under constant stirring and the obtained compounds were as follows: (I) Ba[(C9 H4 ONBr2 )2 ]⋅1.5H2 O; (II) Ba[(C9 H4 ONCl2 )(OH)]⋅1H2 O; (III) Ba[(C9 H5 ONI)2 ]⋅1H2 O and (IV) Ba[(C9 H4 ONICl)2 ]⋅5H2 O, respectively. The compounds were characterized by elemental analysis, infrared absorption spectrum (IR), inductively coupled plasma spectrometry (ICP), simultaneous thermogravimetry-differential thermal analysis (TG-DTA) and differential scanning calorimeter (DSC). The final residue of the thermal decomposition was characterized as orthorhombic BaBr2from (I); the intermediate residue, as a mixture of orthorhombic BaCO3 and BaCl2 and cubic BaO and the final residue, as a mixture of cubic and tetragonal BaO and orthorhombic BaCl2 (II); the intermediate residue, as orthorhombic BaCO3 and as a final residue, a mixture of cubic and tetragonal BaO from (III); and the intermediate residue, as a mixture of orthorhombic BaCO3 and BaCl2 and as a final residue, a mixture of cubic and tetragonal BaO and orthorhombic BaCl2 from (IV).
Abstract
Tin(II) complexes with 8-hydroxyquinolinate in solid state have been obtained by adding aqueous ammonium to a solution containing stannous chloride and 8-hydroxiquinoline in medium of HCl and acetone up to pH 5 and 9, respectively. The products obtained show the same composition, Sn(C9H6ON)2; however there are some differences regarding both the thermal behaviour in an oxidant atmosphere and morphology. These products were characterised by elemental and complexometric analysis, TG and DTA curves, infrared and X-ray diffractometry. TG curves show, above 448 K, the partial oxidation on air atmosphere of Sn(II) complexes to Sn(IV) complexes, SnO(C9H6ON)2. This behaviour does not depend only on pH in which the compounds were obtained but also on the heating rate in TG curves. Sn(II) complexes volatilise almost completely on nitrogen atmosphere and partially on air atmosphere depending on the oxidation degree of the compound.
