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Cr1.8Ti0.2O3+z (CTO) particles were grown by a sol–gel route followed by two thermal treatments at 1273 K. Magnetic susceptibility studies showed a para- to antiferromagnetic transition at around 3...

In this work, we studied the cation occupancy of bimagnetic CoO/Co1−xZnxFe2O4 core/shell nanoparticles by means of X-ray absorption and Mossbauer spectroscopies, which provide element-sensitive information at the atomic scale. Our results indicate that, although the spinel ferrite forms a multi-grain shell, the Zn cations occupy solely tetrahedral sites, while the Co cations are mostly in the octahedral site. On the other hand, the Fe cations are distributed in both tetrahedral and octahedral sites for all concentrations. Also the results provide evidence for a Zn-deficient spinel with an excess of Co cations in the shell, whose origin is further rationalized in terms of the two-step synthesis process. In overall, this work gives a description of the cation occupancy in the core/shell nanoparticles and can serve as a guide to the interpretation of the magnetic properties of complex bimagnetic systems for future technological applications.

Oxides with proton conductivity have a great potential for applications in environmental energy technology. Despite the BaCe0.4Zr0.4Y0.2O3−δ (BCZY) perovskites being well-known proton conductors, it is a challenge to determine the optimal operating temperature range where the energy applications benefit most from this unique property. The protonic transport properties strongly depend on crystal structure and local distortions in the participating cation coordination sphere, according to related temperatures and gas feed. The transport and crystallographic properties of BCZY were simultaneously studied by impedance spectroscopy (IS) and synchrotron X-ray diffraction (S-XRD). A strong correlation between conductivity and the lattice parameter, corresponding in principle to a cubic symmetry, was observed, mainly between 400 and 700 °C. The protonic conductivity range was analyzed by the H/D isotopic effect on the impedance spectra, which helped to identify protonic conduction as the governing transport mechanism below 600 °C, while the transport via oxygen vacancies dominates above this temperature. In order to assess the real crystallographic structure, the simultaneous refinement of laboratory XRD and neutron diffraction (ND) patterns was performed. According to this, BCZY changes from rhombohedral symmetry below 400 °C to cubic at 600 °C in a second-order phase transition. Complementary quasielastic neutron scattering (QENS) enables us to determine a protonic jump length of 3.1 Å, which matches the O–O distances in the octahedral oxygen coordination sphere around the cations. These results support the protonic self-diffusion through proton hopping between intraoctahedral O sites as the main transport mechanism up to 600 °C., This work was supported by Agencia Nacional de Promocion de Ciencia y Tecnologia (ANPCyT) PICT-2016-2965 and PICT2014-1849, CONICET PIP-2015-0565, LNLS (Brazil), under proposals 20150099 and 20170278, and ILL (France) under proposal 7-03-168. L. Giebeler is grateful to the German Federal Ministry of Education and Research (BMBF) and the Argentinian Ministry of Science and Technology (MinCyT) for funding in the bilateral project DeFLeST (01DN14002). J. A. Alonso thanks the Spanish Ministry for Science, Innovation and Universities for funding the Project MAT2017-84496-R.

In this work nanostructured CeO2-ZrO2-Sc2O3 mixed oxides prepared by citrate complexation method are studied. The effects of the co-substitution of ZrO2 and Sc2O3 in the CeO2 lattice are assessed in terms of the reducibility of the samples and their catalytic activity towards oxidation of methane. In situ X-ray absorption near edge structure (XANES) and X-ray powder diffraction (XPD) experiments with synchrotron light were performed to study the oxygen exchange capacity of these ternary oxides in reaction conditions and their structure stability. Catalytic experiments for complete methane combustion indicated a superior performance of samples containing Sc2O3 compared to the CeO2-ZrO2 one in terms of reaction onset temperature, conversion values and activation energy. Samples with 4 at% and 6 at% Sc doping exhibited a stable behavior at 800 °C during 7.5 h on-stream experiments. Structural stability was confirmed by in-situ XPD experiments with no secondary phase segregation or carbon deposition in reaction conditions. Fil: Toscani, Lucía María. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina Fil: Curyk, Pablo Andrés. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Ingeniería Química; Argentina Fil: Zimicz, Maria Genoveva. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina Fil: Halac, Emilia Beatriz. Comisión Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones No Nucleares. Gerencia Física (CAC). Departamento de Física de la Materia Condensada; Argentina Fil: Saleta, Martin Eduardo. Comision Nacional de Energia Atomica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia.; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina Fil: Lamas, Diego Germán. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina Fil: Larrondo, Susana Adelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; Argentina

Fil: Saleta, Martin Eduardo. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Bariloche | Comision Nacional de Energia Atomica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Bariloche.; Argentina. Comision Nacional de Energia Atomica. Gerencia del Area de Energia Nuclear. Instituto Balseiro; Argentina

Nanoparticles (NPs) with magnetic properties based on magnetite (Fe3O4, MAG) modified with oleic acid (OA), chitosan (CS) and bovine serum albumin (BSA) have been prepared. A versatile method of synthesis was employed, involving two steps: (i) co-precipitation of MAG; and (ii) nanoprecipitation of macromolecules on as-formed MAG NPs. Experimental variables have been explored to determine the set of conditions that ensure suitable properties of NPs in terms of their size, functionality and magnetic properties. It was found that the presence of OA in Fe+2/Fe+3 solutions yields MAG NPs with lower aggregation levels, while increasing initial amounts of OA may change the capability of NPs to disperse in aqueous or organic media by modifying the stabilization mechanism. Incorporation of CS was verified through Fourier transform IR spectroscopy. This biopolymer stabilizes NPs by electrostatic repulsions leading to stable ferrofluids and minimal fraction of recoverable solid NPs. BSA was successfully added to NP formulations, increasing their functionality and probably their biocompatibility. In this case too stable ferrofluids were obtained, where BSA acts as a polyelectrolyte. From the proposed methodology it is possible to achieve a wide range of NPs magnetically active intended for several applications. The required properties may be obtained by varying experimental conditions. Fil: Nicolás, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Planta Piloto de Ingeniería Química (i); Argentina. Universidad Nacional del Sur; Argentina Fil: Saleta, Martin Eduardo. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina Fil: Troiani, Horacio Esteban. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina Fil: Zysler, Roberto Daniel. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina Fil: Lassalle, Verónica Leticia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentina Fil: Ferreira, Maria Lujan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Planta Piloto de Ingeniería Química (i); Argentina. Universidad Nacional del Sur; Argentina

of ferromagnetic La0.5Sr0.5CoO3 (LSCO) and multiferroic BiFeO3 (BFO) were synthesized by spray pyrolysis method. Different compositions of multiferroic xLSCO-(1-x)BFO composites were synthesized at 800 °C for 2 h. Scanning electron microscopy and energy dispersive spectroscopy elemental mapping were performed to study the morphology of composites. Ferri/ferromagnetic responses above TC (LSCO) are observed, which are associated with the interfaces LSCO/BFO. This interface presents a different behavior compared to the original perovskites, and the magnitude of the magnetization depends on x. Electrical DC conductivity as a function of temperature for LSCO nanopowder (x = 1) presents a different behavior than that reported in bulk material. For x = 1 and 0.9, the model by Glazman and Matveev [Zh. Eksp. Teor. Fiz. 94, 332 (1988)] is proposed to describe the electrical conductivity. On the other hand, x = 0, 0.1, and 0.5 present a variable range hopping behavior. Complex impedance spectroscopy as a function of frequency indicates a pure resistive behavior for x ≥ 0.5 compositions, while a complex resistive-capacitive behavior is observed for low x values (0, 0.1). In these samples, low values of magnetoelectric coupling were measured with an AC lock-in technique. Fil: Lohr, Javier Hernán. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina Fil: Lopez, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; Argentina Fil: Saleta, Martin Eduardo. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina Fil: Sanchez, Rodolfo Daniel. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina

We present a crystallographic, morphologic and redox dynamic study on (60:40) NiO/Ce0.9Gd0.1O1.95 (NiO/GDC) cermets simulating Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFC) anodes in situ conditions. We tested micro- and nanometer sized materials at 700ºC in three different atmospheres (5% H2, 5% O2 and 20% CH4). We used Dispersive X-ray Absorption Spectroscopy (DXAS) analysisat the Ce L3-edge and at the Ni K-edge to follow the metal´s oxidation states. A correlation between the catalytic/redox properties and the sample´s characteristics (microstructure, Ni distribution, etc.) was found, indicating that nanometric sized particles showed faster and higher reduction extents than micrometric particles of the same composition. Fil: Fernandez Zuvich, Afra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina Fil: Larrondo, Susana Adelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Ingeniería Química. Laboratorio de Procesos Catalíticos; Argentina Fil: Saleta, Martin. Laboratório Nacional de Luz Síncrotron; Brasil Fil: Napolitano, Federico Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina Fil: Caneiro, Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina Fil: Troiani, Horacio Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina Fil: Lamas, Diego Germán. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Arce, Mauricio Damián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina Fil: Serquis, Adriana Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina Fil: Soldati, Analía Leticia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina

Polycrystalline Sr3MnMo2O9 (I) and Ba3MnMo2O9 (II) double perovskites with Mo5+ valence states are prepared by thermal treatment of gels produced from stoichiometric amounts of Sr(NO3)2 or Ba(NO3)2, MnCO3, and (NH4)6Mo7O24 dissolved in citric acid (5% H2/N2 reducing atmosphere, 1200 °C, 12 h).

We prepared the antiferromagnetic Ca 2 CoWO 6 , Sr 2 CoWO 6 and Ba 2 CoWO 6 double perovskites with different crystalline structures, which are monoclinic, tetragonal and cubic respectively. The crystalline structures affect the Co–O distances and the local octahedral symmetry. Magnetic susceptibility experiments were performed as a function of magnetic field and temperature. We found that the effective magnetic moment ( μ eff ) of Co 2+ is partially unquenched and we also found that μ eff increases with the average of Co–O distances that form the CoO 6 octahedra. A simple model associates the behavior of the effective magnetic moment with crystal field effects.

Sr3MnMo2O9 and Ba3MnMo2O9 double perovskites with Mo5+ valence states have been prepared in polycrystalline form by thermal treatment, in reducing atmosphere (H2/N2 flow), of previously decomposed citrate precursors. These materials have been studied by X-ray and neutron powder diffraction (XRPD, NPD), magnetic and transport measurements. At room temperature, the crystal structure of Sr3MnMo2O9 is monoclinic, space group P21/n, with a = 5.6564(1) Å, b = 5.6383(1) Å, c = 7.9765(2) Å, β = 89.994(7)º; whereas Ba3MnMo2O9 presents a cubic lattice, space group Fm m, with a = 8.14900(8) Å. These samples present a frustrated magnetic interaction below to 12 and 9 K for Sr3MnMo2O9 and Ba3MnMo2O9, respectively. Semiconductor behaviour, observed either from d.c. or a.c. measurements, was modelled by a variable-range hopping mechanism. This transport behaviour is in accord with the electronic configurations Mn2+(3 d5)–Mo5+(4 d1) and supports the absence of mixed valence states in both double perovkites., J.C.P. thanks CONICET (Project PIP 112-200801-01360), SECyT-UNSL (Project PROICO 2-7707- 22/Q823) and ANPCYT (Project PICT 6/25459). R.D.S. thanks UN Cuyo, CONICET and ANPCyT (Argentina) under grants 06/C389, PIP-490 and PICT2007-0832/PICT2011-0752. J.A.A. acknowledges the financial support of the Spanish Please provide the grant number for: 1) Ministry of Education, 2) Brazilian Synchrotron Light Laboratory, if any.Ministry of Education to the project MAT2013-41099-R.

We present a magnetic study of vanadium oxide nanotubes (VOx-NTs) with polyaniline (PAni). Transmission electron microscopy (TEM) shows the tubular shape and the multi-wall structure of the nanotubes. The static magnetic susceptibility measured at different magnetic fields shows a Curie behavior, while the magnetization versus magnetic field presents a non-linear dependence at low temperatures. Both experiments can be explained by the presence of paramagnetic ions with S = 1/2. Using Electron Paramagnetic Resonance technique, we identified as V4+(3d1) the paramagnetic ions present in the nanostructures. All the experimental results can be explained by a fraction between 14% and 18% of V4+ with respect to the total V atoms in the system.

In this work, we present a characterization of a hybrid nanocomposite constituted by vanadium oxide (VO x )/ hexadecylamine (Hexa) and the effect of the addition of Ni ions on the magnetic properties. Micrographs of transmission electron microscopy (TEM) show that the nanostructures are multiwall nanotubes. The walls are constituted by the successive intercalation of VO x and Hexa layers. The number of vanadium atoms and the ratio Ni/V were measured by instrumental neutron activation analysis (INAA) and by energy dispersive spectroscopy (EDS), respectively. Measurements of electronic paramagnetic resonance (EPR) and DC magnetic susceptibility, as a function of temperature, reveal that the Ni doping reduces considerably the amount of V 4+ present in the system.

There is a wide number of different synthetic methods to obtain magnetite (Fe3O4) superparamagnetic nanoparticles (SPNPs). However, only a few are able to produce very small and well defined SPNPs with narrow size distribution. We report a modification of the metal-complex decomposition in organic media method in which we replace iron(III) acetylacetonate (Fe(Acac)3) with an iron–urea complex (Fe-Urea) as metal source for the synthesis. With this modification we were able to obtain small particle sizes with a good control in size distribution. The Fe-Urea complex is easy to prepare with excellent yields. Core–shell nanoparticles are then prepared using palladium(II) acetylacetonate as a Pd source, to obtain a Pd0 shell stabilised by oleylamine. The core–shell superparamagnetic nanoparticles of Fe3O4@Pd-OA are extensively characterized by FT-IR, powder X-ray diffraction, transmission electron microscopy, UV-vis, thermogravimetric analysis/differential scanning calorimetry, and magnetic susceptibility measurements, and tested in a palladium-catalyzed cross-coupling Suzuki–Miyaura reaction with promising results. Fil: Cappelletti, Ariel Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina Fil: Uberman, Paula Marina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina Fil: Martín, Sandra Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina Fil: Saleta, Martin Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Universidad Nacional de Cuyo; Argentina Fil: Troiani, Horacio Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Universidad Nacional de Cuyo; Argentina Fil: Sanchez, Rodolfo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Universidad Nacional de Cuyo; Argentina Fil: Carbonio, Raul Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Fisicoquímica; Argentina Fil: Strumia, Miriam Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina

We present a simple and inexpensive experiment to study the drainage of a cylindrical vessel. The experiment consists of a transparent cylinder and a webcam or a digital camera connected to a computer. The model proposed to explain the results makes use of Bernoulli’s equation for real flows including energy losses. The experimental results are well explained by the model, which is a generalization of Torricelli’s expression.

We present the results of an experimental study of the implications of the Neumann and Dirichlet boundary conditions on the solution of two-dimensional electrostatic problems. The experimental setup is simple and low cost. The experimental results are compared with theoretical expectations using a spreadsheet program to solve Laplace’s equation with the appropriate boundary conditions. Excellent agreement is found between the experimental results and the calculations. The simplicity of the experiment and of the theoretical interpretation makes this experiment accessible to beginning students.

The new double-perovskite of title is prepared by decomposition of citrate precursors obtained from Ba(NO3)2, Fe(NO3)3, and (NH4)6Mo7O24 (air, 180600 °C, 12 h) followed by thermal treatment under 5% H2/N2 (800 °C, 12 h).

A polycrystalline Ba2Fe2/3Mo4/3O 6 double-perovskite has been prepared by decomposition of citrate precursors and subsequent thermal treatment under a reducing atmosphere. The crystal structure has been studied by combined X-ray and neutron powder diffraction (XRPD and NPD). At room temperature, the structure is cubic (Fm3̄m) with lattice parameter a = 8.0710(1) Å. It is unchanged between 3 and 320 K. The crystallographic formula is Ba2[Fe 0.52(2)Mo0.48(2)]4a[Fe0.14(2)Mo 0.86(2)]4bO5.9(2). NPD, electron spin resonance (ESR), and magnetization measurements show spontaneous magnetization below the Curie temperature (TC) = 310 K. The ESR behavior is associated with the presence of localized Fe3+ ions, whereas the transport properties (electrical conductivity and Seebeck effect) suggest the presence of highly correlated electrons in a metallic band with disorder, which can be associated with the Mo t2g electrons. The coexistence of localized and itinerant electrons leads to non-negligible magnetoresistance properties., J. C. P. thanks Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (project PIP 112‐200801‐01360), Secretaría de Ciencia y Tecnología de la Universidad Nacional de San Luis (SECyT‐UNSL) (project PROICO 2‐7707‐22/Q823), and Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT) (project PICT 6/25459). R. D. S. thanks Universidad Nacional de Cuyo (UNCuyo), CONICET, and ANPCyT (Argentina) under grants 06/C389, PIP‐490, and PICT2007‐0832/PICT2011‐0752. J. C. P., R. D. S., C. A. L., and M. E. S. are members of CONICET. J. A. A. acknowledges the financial support of the Spanish Ministry of Education on the project MAT2007‐60536.

Polycrystalline Ca3MnIII2WO9 (I) and Ca3MnIII/IV2NbO9 (II) are prepared by calcination in air of stoichiometric mixtures of CaCO3, MnCO3, and WO3 (or Nb2O5) (Pt crucible, 800 °C, 12 h).

Since reactor pressure vessel steels are ferromagnetic, provide a convenient means to monitor changes in the mechanical properties of the material upon irradiation with high energy particles, by measuring their magnetic properties. Here, we discuss the correlation between mechanical and magnetic properties and microstructure, by studying the flux effect on the nuclear pressure vessel steel used in reactors currently under construction in Argentina. Charpy-V notched specimens of this steel were irradiated in the RA1 experimental reactor at 275 C with two lead factors (LFs), 93 and 183. The magnetic properties were studied by means of DC magnetometry and ferromagnetic resonance. The results show that the coercive field and magnetic anisotropy spatial distribution are sensitive to the LF and can be explained by taking into account the evolution of the microstructure with this parameter. The saturation magnetization shows a dominant dependence on the accumulated damage. Consequently, the mentioned techniques are suitable to estimate the degradation of the reactor vessel steel. Fil: Kempf, Rodolfo A.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina Fil: Sacanell, Joaquin Gonzalo. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina Fil: Milano, Julian. Comision Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Bariloche). División Resonancias Magnéticas; Argentina Fil: Guerra Mendez, Nicolas. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina Fil: Winkler, Elin Lilian. Comision Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Bariloche). División Resonancias Magnéticas; Argentina Fil: Butera, Alejandro Ricardo. Comision Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Bariloche). División Resonancias Magnéticas; Argentina Fil: Troiani, Horacio Esteban. Comision Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Bariloche). División Resonancias Magnéticas; Argentina Fil: Saleta, Martin Eduardo. Comision Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Bariloche). División Resonancias Magnéticas; Argentina Fil: Fortis, Ana Maria. Comisión Nacional de Energía Atómica; Argentina

Structural, magnetic and electrical transport properties were studied in the solid solution Y x Sr 1− x MnO 3 for the range of 0.4⩽ x ⩽0.9. These compounds were obtained in the perovskite phase (ABO 3 ) and scan a wide range of mean ionic radii for the A site and the corresponding tolerance factor. The samples were synthesized using a liquid mix method, at 900 °C in O 2 atmosphere, and characterized by X-ray powder diffraction (XRD), magnetic susceptibility and electric transport measurements. XRD data for all samples were refined by the Rietveld method in the space group Pnma. Magnetic measurements indicate a paramagnetic behavior in the range between 100 and 300 K. The dependence of structural parameters, like octahedron distortion and A site coordination number as a function of Y content was obtained showing a clear correlation with the magnetic behavior.

Recent studies have shown that the addition of Ca as host ion in the layered compounds RBaCo2O5+δ (with R a rare earth or yttrium) produces a dramatic effect on their magnetic properties, as well as on their Seebeck coefficient and resistivity. Studies performed so far have opened up the possibility that the substitution site for Ca atoms might not be obvious, having been reported at the Y site, at the Ba site, or regarded as not decisive to the ferromagnetism enhancement. In this work, we present a comparative study of Ca-doped cobaltite samples synthesized with two different nominal substitution sites, namely, Ca replacing Ba, and Ca replacing Y. X-ray absorption spectroscopy performed at the Ca, Ba, and Co edges to study the local environment around these elements allowed to unequivocally determine that the substitutional site of Ca is the Y site. This important result helps to clarify the mixed valence state of cobalt as Co3+ and Co4+, which would be responsible for the ferromagnetic interactions, and explains the antiferromagnetic to ferrimagnetic switch occurring already at 10% Ca doping level. Fil: Aurelio, Gabriela. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física. Laboratorio de Resonancias Magnéticas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Bardelli, F.. Institut des Sciences de la Terre; Francia Fil: Junqueira Prado, R.. Universidade Federal de Mato Grosso Do Sul. Centro de Ciecias Exactas E Tecnología; Brasil Fil: Sanchez, Rodolfo Daniel. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física. Laboratorio de Resonancias Magnéticas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Saleta, Martin Eduardo. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física. Laboratorio de Resonancias Magnéticas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Garbarino, G.. European Synchrotron Radiation Facility (ESRF); Francia

We describe the preparation, crystal structure determination, magnetic and transport properties of two novel Mn-containing perovskites, with a different electronic configuration for Mn atoms located in B site. Ca3Mn 3+ 2WO9 and Ca3Mn 3+/4+ 2NbO9 were synthesized by standard ceramic procedures; the crystallographic structure was studied from X-ray powder diffraction (XRPD) and neutron powder diffraction (NPD). Both phases exhibit a monoclinic symmetry (S.G.: P21/n); Ca3Mn 2WO9 presents a long-range ordering over the B sites, whereas Ca3Mn2NbO9 is strongly disordered. By >in-situ> NPD, the temperature evolution of the structure study presents an interesting evolution in the octahedral size (〈 Mn-OâŒ) for Ca3Mn2NbO9, driven by a charge ordering effect between Mn3+ and Mn4+ atoms, related to the anomaly observed in the transport measurements at T≈160 K. Both materials present a magnetic order below TC=30 K and 40 K for W and Nb materials, respectively. The magneto-transport measurements display non-negligible magnetoresistance properties in the paramagnetic regime.© 2013 Published by Elsevier Inc. All rights reserved., C.A.L. and M.E.S. thanks a CONICET fellowship. J.C.P. thanks CONICET (Project PIP 2008-01360), SECyT-UNSL (Project 7707 and Project 2-1612). R.D.S. acknowledges financial support of ANPCYT (Project PICT 2011-0752) and SEPCyT-UNCu (06/C389). J.C.P. and R.D.S are member of CONICET. J.A.A. acknowledges the financial support of the Spanish Ministry of Education to the project MAT2010-16404.

In this work we present a complete characterization and magnetic study of vanadium oxide/hexadecylamine nanotubes (VOx/Hexa NT’s) doped with Co2+ and Ni2+ ions. The morphology of the NT’s has been characterized by transmission electron microscopy, while the metallic elements have been quantified by the instrumental neutron activation analysis technique. The static and dynamic magnetic properties were studied by collecting data of magnetization as a function of magnetic field and temperature and by electron paramagnetic resonance. At difference of the majority reports in the literature, we do not observe magnetic dimers in vanadium oxide nanotubes. Also, we observed that the incorporation of metallic ions (Co2+, S = 3/2 and Ni2+, S = 1) decreases notably the amount of V4+ ions in the system, from 14−16% (nondoped case) to 2%−4%, with respect to the total vanadium atoms (fact corroborated by XPS experiments) anyway preserving the tubular nanostructure. The method to decrease the amount of V4+ in the nanotubes improves considerably their potential technological applications as Li-ion batteries cathodes.

In this work, we present the synthesis and characterization of a hybrid nanocomposite constituted by iron oxide nanoparticles and vanadium oxide/Hexadecylamine (VOx/Hexa) nanotubes. Transmission Electron Microscopy (TEM) images show small particles (around 20 nm) in contact with the external wall of the multiwall tubes, which consist of alternate layers of VOx and Hexa. By Energy Dispersive Spectroscopy (EDS), we detected iron ions within the tube walls and we have also established that the nanoparticles are composed of segregated iron oxide. The samples were studied by Electron Paramagnetic Resonances (EPR) and dc-magnetization as a function of the magnetic field. The analysis of the magnetization and EPR data confirms that a fraction of the V atoms are in the V4+ electronic state and that the nanoparticles exhibit a superparamagnetic behavior. The percentage of V and Fe present in the nanocomposite was determined using Instrumental Neutron Activation Analysis (INAA). Fil: Saleta, Martin Eduardo. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Troiani, Horacio Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina Fil: Ribeiro Guevara, S.. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina Fil: Sanchez, Rodolfo Daniel. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Malta, M.. Universidade Do Estado Da Bahia; Brasil Fil: Torresi, R.M.. Universidade de Sao Paulo; Brasil

It is well known that CeO2-based materials present excellent catalytic properties for the oxidation of H2 and CH4 fuels [1] and with the incorporation of metal oxides (Gd2O3, Sm2O3, Y2O3) in the CeO2 lattice the oxygen storage capacity, the ionic conductivity and the specific surface area can be significantly improved. Furthermore, the addition of metals such as Ni or Cu enhances the electronic conductivity of the material, thus enabling them as efficient IT-SOFC anodes [2, 3]. A previous study on the microstructure influence in the electrochemical properties of commercial Ce0.9Gd0.1O1.95 (GDC) with several grain sizes, impregnated with NiO [3] to form 40:60 (%wt) composites showed that better performances were achieved with nanocrystalline samples supporting the fact that the optimization of microstructure and morphology are crucial for the development of efficient anodes. A particular approach to optimize the anode microstructure is to tailor its porosity. In this way, the addition of activated carbon in an intermediate step followed by calcination at 1450ºC resulted in an increase of more than 30% in the anode efficiency [4]. Other composite morphologies can be obtained modifying the way that Ni is incorporated into the material. A common procedure is the impregnation method: the GDC material is submerged in a Ni(NO3)2*6H2O solution, dried in an oven at 90ºC and calcinated at 350ºC to generate NiO [4]. In this work, we present a new modified sol-gel method to incorporate Ni into the precursor solution. This route produces a powder with a very homogeneous Ni distribution. Transmission Electron Microscopy (TEM) and Energy Dispersive Spectroscopy (EDS) analysis indicated that this modification resulted in smaller particle sizes with a narrower size-distribution than the observed in commercial Ni-GDC cermets. The study of the oxidation state and coordination of Ce and Ni in these cermets, simulating in-operando conditions, was performed using synchrotron DXAS technique. Electrochemical impedance spectroscopy (EIS) analyses allowed to establish a correlation between the electrochemical properties with the sample´s characteristics (microstructure, Ni distribution, etc.). [1] M.G. Zimicz, S.A. Larrondo, R.J. Prado and D.G. Lamas, Int. Journal of Hydrogen Energy 37 (2012) 14881–14886. [2] W.C. Chueh, Y. Hao, W. Jung and S.M. Haile, Nature Materials 11 (2012) 155-161. [3] M. G. Zimicz, P. Núñez, J. C. Ruiz-Morales, D. G. Lamas, S. A. Larrondo, Journal of Power Sources, vol. 238 (2013) 87-94 [4] A. Fernandez Zuvich, A. Caneiro, C. Cotaro and A, Serquis. Procedia Materials Science 1 (2012) 628-635.

The XDS beamline of the Synchrotron Light National Laboratory (LNLS), was designed to take advantage of the 4T superconducting multipole wiggler inserted in the storage ring. This multipurpose beam line is employed for X-ray diffraction and X-ray absorption spectroscopy in the energy range between 5 and 30 keV. The X-ray diffraction patterns can be acquired in two different arrangements: a) Bragg-Brentano configuration, using a scintillation detector with an analyzer and b) Debye-Scherrer configuration, where the sample is mounted into capillaries and the diffraction pattern is acquired with an arrangement of 6 Mythen detectors or a scintillator. The sample can be measured at different atmospheres and temperatures. The viability of the beamline for pair distribution function analysis (PDF) was tested measuring two different standards: 1) Al2O3 and 2) BaTiO3. The patterns were acquired at room temperature using the two detection setups at an energy of 20 keV. The samples were mounted inside 0.3 mm boron-rich glass capillaries. In addition to the sample pattern, we also measured the empty capillary (background) to subtract it to the sample data. The acquired and normalized patterns were converted into total scattering PDF (G(r)) with the PDFgetX3.[1] The experimental G(r) was fitted with the PDFgui.[2] Both data sets were fitted in the corresponding structural phase with cell parameters close to the ones reported in the literature. In the special case of the BaTiO3 sample, it was very carefully modeled. We particularly focused in evaluating if we can discriminate the correct structural phase, as this sample presents different phases (orthorhombic, tetragonal and cubic). We could identify that the sample, at room temperature, was at the expected tetragonal phase. Finally, we will present a preliminary analysis of the following systems: Pb1-xRxZr1-yTiyO3 (R=La&Ba) and Ba1-xRxZr1-yTiyO3 (R=La&Ca) at the ferro- and paraelectric states by PDF.

Vanadium oxide nanotubes constitute promising materials for applications in nanoelectronics as cathode materials, in sensor technology and in catalysis. In this work we present a study on hybrid vanadium oxide/hexadecylamine multiwall nanotubes doped with Co ions using state of the art x-ray diffraction and absorption techniques, to address the issue of the dopant location within the nanotubes' structure. The x-ray absorption near-edge structure analysis shows that the Co ions in the nanotubes are in the 2 + oxidation state, while extended x-ray absorption fine structure spectroscopy reveals the local environment of the Co(2+) ions. Results indicate that Co atoms are exchanged at the interface between the vanadium oxide's layers and the hexadecylamines, reducing the amount of amine chains and therefore the interlayer distance, but preserving the tubular shape. The findings in this work are important for describing Co(2+) interaction with vanadium oxide nanotubes at the molecular level and will help to improve the understanding of their physicochemical behavior, which is desired in view of their promising applications.

Vanadium oxide nanotubes (NTs) were synthesized by the sol-gel method followed by a long-term hydrothermal treatment. The obtained nanotubes have a multiwall structure, and 70% of vanadium ions are in the V4+ state. This percentage was derived by evaluating three components of the magnetic susceptibility; namely, (i) the paramagnetic Curie-Weiss behavior, (ii) antiferromagnetic dimers, and (iii) magnetic trimers. The as-made NTs were annealed in situ in the cavity of the electron paramagnetic resonance (EPR) spectrometer. The line shape changes irreversibly at 390 K, and the EPR susceptibility presents an anomaly at 425 K. These changes are interpreted as a partial oxidation of the V4+ ions and consequently a decrease in the concentration of the magnetic species. The quantification of the V4+ ions of the annealed NTs reveals a diminution to 39% of V4+, a weakening of the Curie-Weiss and antiferromagnetic dimers contributions, and the suppression of magnetic trimers. Vibrational studies confirm the decreas...

In this work we present an electrical characterization of La2/3Ca1/3MnO3 particles obtained by spray pyrolysis. We optimized the synthesis conditions to obtain the desired compound with the expected structure and the ferromagnetic transition at the same temperature as the bulk material. We found that a post-deposition thermal treatment enhances the magnetic properties of the samples. The study of structural, morphological and magnetic properties shows that the walls of the hollow spheres are constituted by grains on the nanometer scale. The I?V characterization shows typical signatures of tunneling transport. This behavior can be associated with the grain boundaries within the microparticle's wall acting as tunnel barriers.

We have systematically studied the magnetic properties of ferrite nanoparticles with 3, 7, and 11 nm of diameter with very narrow grain size distributions. Samples were prepared by the thermal decomposition of Fe(acac)3 in the presence of surfactants giving nanoparticles covered by oleic acid. High resolution transmission electron microscopy (HRTEM) images and XRD diffraction patterns confirms that all samples are composed by crystalline nanoparticles with the spinel structure expected for the iron ferrite. ac and dc magnetization measurements, as well in-field Mossbauer spectroscopy, indicate that the magnetic properties of nanoparticles with 11 and 7 nm are close to those expected for a monodomain, presenting large MS (close to the magnetite bulk). Despite the crystalline structure observed in HRTEM images, the nanoparticles with 3 nm are composed by a magnetically ordered region (core) and a surface region that presents a different magnetic order and it contains about 66% of Fe atoms. The high saturati...