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See detailStudy of the photocatalytic activity of Fe3+, Cr3+, La3+ and Eu3+ single-doped and co-doped TiO2 catalysts produced by aqueous sol-gel processing
Malengreaux, Charline; Pirard, Sophie ULg; Léonard, Géraldine ULg et al

in Journal of Alloys and Compounds (2017), 691

An aqueous sol-gel process, previously developed for producing undoped and Cu2+, Ni2+, Zn2+ or Pb2+ doped TiO2 photocatalysts with remarkably high photocatalytic activity without requiring any calcination ... [more ▼]

An aqueous sol-gel process, previously developed for producing undoped and Cu2+, Ni2+, Zn2+ or Pb2+ doped TiO2 photocatalysts with remarkably high photocatalytic activity without requiring any calcination step, has been adapted to produce Fe3+, Cr3+, La3+ or Eu3+ single-doped TiO2 photocatalysts as well as La3+-Fe3+ and Eu3+-Fe3+ co-doped TiO2 catalysts. The physicochemical properties of the obtained catalysts have been characterized using a suite of complementary techniques, including ICP-AES, XRD, UV-Vis spectroscopy, nitrogen adsorption-desorption and Fe-57 Mössbauer. The active crystalline phase is obtained without requiring any calcination step and all the different catalysts are composed of nanocrystallites of anatase with a size of 6-7 nm and a high specific surface area varying from 181 to 298 m² g-1. In this study, the effect of the NO3:Ti(IV) mole ratio used to induce the peptisation reaction during the synthesis has been studied and the results revealed that this ratio can influence significantly the textural properties of the resulting catalyst. A screening of the photocatalytic activity of the undoped and Fe3+, Cr3+, La3+ or Eu3+ single-doped and co-doped photocatalysts has been performed by evaluating the degradation of 4-nitrophenol under UV-Visible light (330 nm < λ < 800 nm). This study suggests that the photocatalytic activity is significantly influenced by the dopant nature and content with an optimal dopant content being observed in the case of Fe3+ or La3+ single-doped as well as in the case of La3+-Fe3+ and Eu3+-Fe3+ co-doped catalysts. In the case of Cr3+ single-doped catalysts, a detrimental effect of the dopant on the photocatalytic degradation of 4-nitrophenol has been observed while no significant influence of the dopant has been detected in the case of Eu3+ single-doped catalysts. The role of the different dopants in modulating the photocatalytic activity is discussed. [less ▲]

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See detailStructural, magnetic and magneto-transport properties of monovalent doped manganite Pr0.55K0.05Sr0.4MnO3
Thaljaoui, R.; Boujelben, W.; Pękała, M. et al

in Journal of Alloys and Compounds (2014), 611(0), 427-432

Pr0.55K0.05Sr0.4MnO3 sample have been synthesized using the conventional solid state reaction. Rietveld refinements of the X-ray diffraction patterns at room temperature confirm that the sample is single ... [more ▼]

Pr0.55K0.05Sr0.4MnO3 sample have been synthesized using the conventional solid state reaction. Rietveld refinements of the X-ray diffraction patterns at room temperature confirm that the sample is single phase and crystallizes in the orthorhombic structure with Pnma space group; the crystallite size is around 70 nm. The SEM images show that grain size spreads around 1000–1200 nm. DTA analysis does not reveal any clear transition in temperature range studied. The low-temperature DSC indicates that Curie temperature is around 297 K. Magnetization measurements in a magnetic applied field of 0.01 T exhibit a paramagnetic–ferromagnetic transition at the Curie temperature TC = 303 K. A magnetic entropy change under an applied magnetic field of 2 T is found to be 2.26 J kg−1 K−1, resulting in a large relative cooling power around 70 J/kg. Electrical resistivity measurements reveal a transition from semiconductor to metallic phase. The thermal conductivity is found to be higher than that reported for undoped and Na doped manganites reported by Thaljaoui et al. (2013). [less ▲]

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See detailMagnetic susceptibility and electron magnetic resonance study of monovalent potassium doped manganites Pr0.6Sr0.4−xKxMnO3
Thaljaoui, R.; Pękała, K.; Pękała, M. et al

in Journal of Alloys and Compounds (2013), 580(0), 137-142

The monovalent potassium doped manganites Pr0.6Sr0.4−xKxMnO3 (x = 0.05–0.2) are characterized using the complementary magnetic susceptibility and electron resonance methods. In paramagnetic phase the ... [more ▼]

The monovalent potassium doped manganites Pr0.6Sr0.4−xKxMnO3 (x = 0.05–0.2) are characterized using the complementary magnetic susceptibility and electron resonance methods. In paramagnetic phase the temperature variations of the inverse magnetic susceptibility and the inverse intensity of resonance signal obey the Curie–Weiss law. A similarity in temperature variation of resonance signal width and the adiabatic polaron conductivity points to the polaron mechanism controlling the resonance linewidth. The low temperature limit of the pure paramagnetic phase is determined from the electron resonance spectra revealing the mixed phase spread down to the Curie temperature. [less ▲]

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See detailThermoelectric properties of n-type Ca1-xDyxMn1-yNbyO3-delta compounds (x=0, 0.02, 0.1 and y=0, 0.02) prepared by spray-drying method
Muguerra, Hervé; Rivas-Murias, Beatriz; Traianidis, Maria et al

in Journal Of Alloys And Compounds (2011), 509(29), 7710-7716

We report the high temperature thermoelectric properties of Ca1-xDyxMn1-yNbyO3-delta (x = 0, 0.02, 0.1 and y = 0, 0.02) synthesized by spray-drying method. A maximum power factor (PF) value of 2.65 mu WK ... [more ▼]

We report the high temperature thermoelectric properties of Ca1-xDyxMn1-yNbyO3-delta (x = 0, 0.02, 0.1 and y = 0, 0.02) synthesized by spray-drying method. A maximum power factor (PF) value of 2.65 mu WK-2 cm(-1) is obtained at 1100 K for CaMn0.98Nb0.02O3-delta. This represents an improvement of about 75% with respect to undoped CaMnO3-delta sample at the same temperature. We also provide a complete structural characterization of the samples. (C) 2011 Elsevier B.V. All rights reserved. [less ▲]

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See detailRadiative lifetime measurements and transition probability calculations in lanthanide ions
Quinet, Pascal ULg; Palmeri, P.; Biémont, Emile ULg et al

in Journal of Alloys and Compounds (2002), 344(1-2), 255-259

We have undertaken a systematic investigation of spectroscopic properties of lanthanide ions (Z=57-71). Using time-resolved laser-induced fluorescence following one- or two-photon excitations, a large ... [more ▼]

We have undertaken a systematic investigation of spectroscopic properties of lanthanide ions (Z=57-71). Using time-resolved laser-induced fluorescence following one- or two-photon excitations, a large number of radiative lifetimes have been measured at the Lund Laser Centre for singly, doubly and trebly ionized atoms. These new measurements have been used for testing theoretical calculations performed within the framework of a relativistic Hartree-Fock approach taking core-polarization effects into account. Using the experimental lifetimes (when available) and the theoretical branching fractions, a large number of transition probabilities, most of them of astrophysical interest, have been deduced and are stored in a new database (DREAM). Up to now, the results obtained concern the following ions: La2+, Ce2+, Ce2+, Pr2+, Ho2+, Er2+, Tm2+, Tm2+, Yb2+, Yb2+, Yb2+, Lu2+ and Lu2+. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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