Chelating agent effects in the synthesis of mesoscopic-size superconducting particles

Motta, M.; Deimling, Cesar Vanderlei; Saeki, Margarida Júri; Lisboa‐Filho, Paulo Noronha

doi:10.1007/s10971-007-1673-0

Cited by 39 publications

(34 citation statements)

References 15 publications

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“…In the so-called sol-gel process, there are many variations in the routes used for preparing samples. A deeper understanding of complexes between α-hydroxycarboxylic acids and metals (M) that are formed on those routes is desirable, since these compounds are highly effective in obtaining heterometallic advanced ceramics 1 . Several metallic ions with different applications have been employed in this kind of route, such as lithium ion in the manufacturing of cathodes for fuel cells 2,3 and barium ion in pellets of high temperature superconductors [4][5][6] , magnetic materials 7,8 , and multiferroic materials 9 .…”

Section: Introductionmentioning

confidence: 99%

“…Several metallic ions with different applications have been employed in this kind of route, such as lithium ion in the manufacturing of cathodes for fuel cells 2,3 and barium ion in pellets of high temperature superconductors [4][5][6] , magnetic materials 7,8 , and multiferroic materials 9 . The modified polymeric precursors method (MPPM) 1,4 involves the polyesterification process of a metal chelate complex using a hydroxycarboxylic acid and a polyhydroxy alcohol in an aqueous solution, which turns into a polymeric gel. In this method, the most commonly employed carboxylic acid is citric acid (CA) 4 .…”

Section: Introductionmentioning

confidence: 99%

“…In this method, the most commonly employed carboxylic acid is citric acid (CA) 4 . The MPPM method has been widely used, since it allows for the preparation of polycrystalline samples of excellent quality, obtaining a highly homogeneous ceramic powder with nanometer-scale particles, and it is reactive at temperatures up to 30% lower than the ceramic powders obtained by traditional routes 1,5 .…”

Section: Introductionmentioning

confidence: 99%

“…As mentioned, the main goal of this method is to obtain a ceramic powder using polymeric precursors via α-hydroxycarboxylic acid and ethylene glycol. There are two sequential chemical reactions involved in these methods 1 . The first, which is the purpose of our theoretical studies, is the chelation between the α-hydroxycarboxylic acid and metal ions obtained from simple salts, such as oxides or carbonates.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical investigation of geometric configurations and vibrational spectra in citric acid complexes

et al. 2014

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The performance of advanced electronic ceramics is directly related to the synthesis route employed. Sol-gel methods are widely used for this purpose. However, the physicochemical intermediate steps are still not well understood. Better understanding and control of these processes can improve the final quality of samples. In this work, we studied theoretically the formation of metal complexes between citric acid and lithium or barium metal cations with different citric acid/metal proportions, using Density Functional Theory electronic structure calculations. Infrared and Raman scattering spectra were simulated for the more stable geometric configurations. Using this methodology, we identified some features of complexes formed in the synthesis process. Our results show that the complexes can be distinguished by changes in the bands assigned to C=O, COH-, and COO -group vibrations. An estimate of the most stable complexes is made based on total energy.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Theoretical investigation of geometric configurations and vibrational spectra in citric acid complexes

et al. 2014

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“…The esterification of EDTA with EG is verified by the appearance of asymmetric stretching modes at 1093 cm -1 and 1338 cm -1 referring to C-O-C and =C-O-C groups, respectively. [35] These modes become more pronounced with the increasing temperature and are presented in the inset of Figure 2. As confirmed later on by XRD and TEM analyses, cross-linking of chemical bonds in the polymeric precursor resulted in the formation of a pure YAG phase.…”

Section: The Polymer Precursormentioning

confidence: 92%

Synthesis of Cerium‐Activated Yttrium Aluminate Based Fine Phosphors by an Aerosol Route

et al. 2012

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Polycrystalline fine powders of yttrium aluminate doped with Ce3+ were synthesised by spray pyrolysis of a polymeric precursor, which was obtained by dissolving the corresponding nitrates in a solution of ethylenediaminetetraacetic acid (EDTA) in ethylene glycol (EG). Aerosol decomposition was performed at 550 °C followed by an additional thermal treatment (900–1100 °C). The yield of either a single yttrium aluminium perovskite (YAP) phase or a single yttrium aluminium garnet (YAG) phase was investigated as a function of the predefined yttrium/aluminium ratio, the cerium doping concentration, the processing temperature, and the thermal‐treatment regime, which included the variation of the heating and cooling rates (dT/dt), the residence time (τ), and the atmosphere. Changes in the composition and structure of the precursor during thermal decomposition were investigated by thermogravimetric and differential thermal analysis (TGA/DTA) and FTIR spectroscopy. The particle morphology and structure were analysed by a combination of scanning electron microscopy and energy‐dispersive X‐ray spectroscopy (SEM/EDS) and by high‐resolution transmission electron microscopy (HR‐TEM). The structural refinement was based on the phase identification performed by X‐ray powder diffraction (XRPD). The emission spectra were recorded within the range 325–800 nm by applying excitation wavelengths of 297 (YAP) and 450 nm (YAG). The employed synthesis conditions assured the formation of spherical, non‐agglomerated particles with well‐developed surfaces and diameters between 200 and 800 nm. For a predefined Y/Al ratio of 1:1, lower processing temperatures combined with longer heat treatments under stationary conditions resulted in a multiphase system, composed of YAP, YAG, and monoclinic yttrium aluminate (YAM) phases. However, a short heat treatment with a high heating rate (200 °C/min) at higher temperatures results in the formation of a kinetically favoured pure YAP hexagonal phase. On the other hand, for a predefined Y/Al ratio of 3:5, the generation of a thermodynamically favoured pure YAG phase has been confirmed, regardless of the applied heat‐treatment conditions. Although incomplete, Ce3+ introduction into the host matrix has been detected by XRPD and luminescence measurements.

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Solution blow spinning control of morphology and production rate of complex superconducting YBa2Cu3O7−x nanowires

Rotta

Motta

Pessoa

et al. 2019

J Mater Sci: Mater Electron

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The demand for nanostructured materials can increase exponentially due to the miniaturization of devices and their potential application in different areas, such as electronic and medicine. Therefore, high production rates are essential for making nanomaterials commercially available. When electrospinning (ES) and solution blow spinning (SBS) are employed for producing ceramic nanostructures, the solution injection rate can influence the morphology without, however, supply the real ceramic production rate. In this work, complex superconducting YBa2Cu3O7-x wires were prepared by using the SBS technique. We also show that the morphology can be controlled by varying the injection rate of the polymer solution and the production rate is 4.7 to 33 times higher than the rates of equivalent ceramics produced by ES. Additionally, we also suggest the term Ceramic Production Rate to refer to the production rate of ceramic structures.

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Chelating agent effects in the synthesis of mesoscopic-size superconducting particles

Cited by 39 publications

References 15 publications

Theoretical investigation of geometric configurations and vibrational spectra in citric acid complexes

Theoretical investigation of geometric configurations and vibrational spectra in citric acid complexes

Synthesis of Cerium‐Activated Yttrium Aluminate Based Fine Phosphors by an Aerosol Route

Solution blow spinning control of morphology and production rate of complex superconducting YBa2Cu3O7−x nanowires

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