Person:
Fernández Castillo, Jesús

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First Name
Jesús
Last Name
Fernández Castillo
URI
https://hdl.handle.net/20.500.14352/76208
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Química Física
Area
Química Física
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2011 - 20133
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End date: 2019 × Start date: 2010 ×

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    Preparation and characterization of Ce0.95Zr0.05O2 nanopowders obtained by solegel and template methods
    (Materials Chemistry and Physics, 2012) Isasi Marín, Josefa; Pérez Estébanez, Marta; Fernández Castillo, Jesús; Correcher, Virgilio; Aldama, Iván; Arévalo, Pablo; Carbajo, María Carmen
    Ce0.95Zr0.05O2 nanopowders have been prepared by a standard Pechini-type solegel process and by using polymethyl methacrylate (PMMA) colloidal crystals as template. The effects of these different synthesis routes, on the structure and microstructural features of the nanopowders, were evaluated by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and specific surface area measurements. For both preparation routes, the XRD analysis has shown that a cubic fluorite structure is formed with a crystallite size of w45e50 nm. The SEM images indicate that the powder obtained by the solegel Pechini-type process, is constituted by aggregated nanoparticles with relatively uniform shape and size, whereas the powder synthesized as inverse opal exhibits the formation of macropores with a mean size of w130 nm. The specific surface areas of the powder samples obtained by the Pechini-type solegel and inverse opal methods are w56 m2 g 1 and w90 m2 g 1 respectively. Additionally, the thermoluminescence (TL) signal of the synthetized samples has been measured in order to examine its potential application in the field of dosimetry of ionizing radiations.
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    Structural and luminescence characterization of synthetic Cr-doped Ni3(PO4)2
    (Journal of Physics and Chemistry of solids, 2013) Correcher, Virgilio; Isasi Marín, Josefa; Cubero, Ágata; Pérez Estébanez, Marta; Aldama, Iván; Arévalo, Pablo; Fernández Castillo, Jesús; García Guinea, Javier
    Ni3–xCr2x/3(PO4)2 (x¼0 and 0.02) microcrystalline powders were obtained as single phases via a modified sol–gel Pechini-type in situ polymerizable complex method. The samples were characterized using scanning electron microscopy, X-ray diffraction, cathodoluminescence (CL), and thermoluminescence (TL) techniques. We found that Cr3+ doping modified the average particle and distribution. The mean particle size was 0.441 μm for Ni3(PO4)2 and 0.267 μm for Ni2.98Cr0.013(PO4)2. The results also reveal that Cr3+ doping notably enhanced the CL and TL UV-blue emission.
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    Structural and cathodoluminiscent properties of Zr0.95Ce0.05O2 nanopowders prepared by sol–gel and template methods
    (Journal of Luminescence, 2011) Fernández Castillo, Jesús; Isasi Marín, Josefa; Pérez Estébanez, Marta; Aldama, Iván; Arévalo, Pablo; Díaz-Guerra Viejo, Carlos
    Nanopowders of Zr0.95Ce0.05O2 composition have been prepared by a standard Pechini-type sol–gel process and by means of a colloidal crystal template approach. In the latter method, inverse opal Zr0.95Ce0.05O2 powders were fabricated employing poly(methylmethacrylate) (PMMA) colloidal crystals as a template.The effects of the two different synthesis routes on the structure and microstructural characteristics of the prepared nanopowders were evaluated by X-ray diffraction and scanning electron microscopy. For both preparation routes, the X-ray diffraction analysis has shown that a tetragonal fluorite structure is formed with a crystallite size of 35–40 nm. The scanning electron microscopy measurements indicate that the powder obtained by the sol–gel Pechini-type process is comprised of nanoparticles that are arranged in agglomerates with shape and size relatively uniform whereas the inverse opal Zr0.95Ce0.05O2 nanopowders exhibit the formation of macropores with a mean size of 100 nm. The cathodoluminescence spectra of the prepared Zr0.95Ce0.05O2 nanomaterials have been measured in the 300–800 nm wavelength range. The powder prepared by sol–gel method yields a broad emission band centered at 482nm whereas the emission from the inverse opal preparation is considerably less intense.