Person:
Prado Gonjal, Jesús De La Paz

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First Name
Jesús De La Paz
Last Name
Prado Gonjal
URI
https://hdl.handle.net/20.500.14352/76087
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Química Inorgánica
Area
Química Inorgánica
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2011 - 20122
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Author: Prado Gonjal, Jesús De La Paz × Subject: 620 ×

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Now showing 1 - 2 of 2
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    Microwave-assisted synthesis: A fast and efficient route to produce LaMO3 (M=Al, Cr, Mn, Fe, Co) perovskite materials
    (Materials Research Bulletin, 2011) Prado Gonjal, Jesús De La Paz; Arévalo-López, Ángel Moisés; Morán Miguélez, Emilio
    A series of lanthanum perovskites, LaMO3 (M=Al, Cr, Mn, Fe, Co), having important technological applications, have been successfully prepared by a very fast, inexpensive, reproducible, environment-friendly method: the microwave irradiation of the corresponding mixtures of nitrates. Worth to note, the microwave source is a domestic microwave oven. In some cases the reaction takes place in a single step, while sometimes further annealings are necessary. For doped materials the method has to be combined with others such as sol–gel. Usually, nanopowders are produced which yield high density pellets after sintering. Rietveld analysis, oxygen stoichiometry, microstructure and magnetic measurements are presented.
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    Increased ionic conductivity in microwave hydrothermally synthesized rare-earth doped ceria Ce1−xRExO2−(x/2)
    (Journal of Power Sources, 2012) Prado Gonjal, Jesús De La Paz; Schmidt, Rainer; Espíndola-Canuto, Jesús; Ramos-Alvarez, Paola; Morán Miguélez, Emilio
    Ce0.85RE0.15O1.925 (RE = Gd, Sm), Ce0.8(Gd0.1Sm0.1)O1.9 and CeO2−δ nano-powders were synthesized by microwave-assisted hydrothermal synthesis in a time and energy efficient way. The fluorite-type crystal structure of the synthesized nano-powders was confirmed by X-ray diffraction (XRD) and Rietveld refinement, and the nano-metric particle sizes calculated from the XRD line width broadening were consistent with transmission electron microscopy observations. The Brunauer–Emmett–Teller method was used to confirm large powder surface area. Scanning electron microscopy confirmed high density and low surface porosity of the sintered ceramics as a result of the high sintering activity of the large surface area nano-powders. Impedance spectroscopy was carried out to separately analyze grain boundary (GB) and bulk dielectric relaxations where GB areas were found to constitute ionic charge transport barriers, because their resistance was larger than that of the bulk. Such barriers were found to be comparatively low due to high GB and bulk ceramic ionic conductivities, with the highest values encountered in the composition Ce0.85Sm0.15O1.925. The optimal ionic conductivities encountered were associated with the effect of high sintering activity of the nano-powders.