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The determination of the structure of Ca(II)-acetate in aqueous solution has been addressed by combining Raman and X-ray absorption fine structure spectroscopies. The pH-dependent speciation of the acetate/Ca(II) system has been studied observing modifications in specific Raman bands of the carboxyl group. The current results evidence the Ca(II)-acetate above acetate pKa forms a bidentate complex and presents a coordination 6, in which the Ca-O shell radius decrease of about 0.1 A with respect the hydrated Ca 2+ with coordination 8. The experimental results show the OCO angle of the carboxyl in the complex is close to 124°, being the OCaO angle about 60°.

Porous-Silicon/Zinc Oxide (PS-ZnO) nanocomposites can be processed by a combination of electrochemical etching of PS and sol-gel infiltration of ZnO, which leads to complex interfaces of ZnO permeated in the PS matrix. In this work, an approach consisting on the determination of transport mechanisms and identification of electroluminescence emission bands from the heterojunction, has been followed to derive the energy band diagram. Charge transport at room temperature has been determined in ITO/PS-ZnO/p+-Si/Al structures through current-voltage characteristics, showing that direct and Fowler-Nordheim (FN) tunneling are the main conduction mechanisms at low and high bias voltages, respectively. White electroluminescence composed of three main bands (~490, ~550 and ~620 nm) is observed at forward bias. Emission starts at a threshold voltage of 3.9±0.2 V, in coincidence with the change in conduction mechanism from direct to FN tunneling. A band diagram of the device is derived from the emission and transport properties, which is coherent with previous electronic and microstructural properties of the starting n-ZnO and p+-Si.

In this work we present an exhaustive investigation about the possibility of using the electrodeposition technique to grow Ga-Fe-O thin films. The morphological and structural characterization has been performed by means of scanning electron microscopy, X-ray diffractometry and X-ray absorption near edge structure measurements. These results have been complemented with chronoamperometric measurements recorded during growth. We have explored different electrolytes, growth potentials, and pH being observed that it is possible to tune the Fe/Ga ratio by means of the potential whereas the surface morphology is closely related to the Na3-citrate content in the electrolyte. The surface roughness is reduced as the Fe content in the layer is increased upon the raise of citrate in the electrolyte composition. X-ray diffractometry indicates that Ga can become partially oxidized, whereas Fe seems to keep its metallic state in its vast majority since we have not obtained clear evidences of oxidation. Thus, this investigation highlights the inherent difficulties to synthetize Ga-Fe-O compounds by means of the electrodeposition technique.

The design of phosphorescent materials, highly crystalline, with a submicron particle size is a challenge for industrial applications. Based on molten salt assisted process, the effects of salt/SrAl0 molar ratio on the phase evolution are studied. A significant influence of salt/SrAl0 molar ratio on synthesis and final properties has been observed. Moreover, the phase evolution has been explored as a function of treatment temperature. To remove the salt from the powder, the wash step is carried out with glycerin avoiding hydrolysis reaction due to the sensitivity of strontium aluminates to water. The salt/SrAl0 molar ratio of 3:1 and the thermal treatment at 1000 0C are preferred, avoiding extra wash step. Here, we have obtained highly crystalline SrAl0:Eu, Dy powder with a particle size =0.5 ≤m after a 2 h treatment at 1000 0C employing the molten salt approach. As a result, we believe that the general strategy described in this study opens the possibility of obtaining technologically relevant phosphors with enhanced properties, expanding their application range to radiation detection., The authors express their thanks to the MINECO (Spain) project MAT2013-480089-C04-1-P for their financial support. Dr. F. Rubio-Marcos is also indebted to MINECO and European Social Fund for a “Juan de la Cierva” contract (ref: JCI-2012-14521).

Changes in Ti K-edge X-ray absorption fine structure (XAFS) spectra of lithium titanium oxide (LTO) during the charge discharge cycle of lithium ion battery were investigated by using a specially designed cell for in situ X-ray measurement. Thought LTO is famous for zero-strain lattice during the charge/discharge cycle, the significant spectral changes might be attributed to Li migration in the lattice. The experimental results were compared with the theoretical simulation, and the spectral changes were caused both by the slight changes in oxygen position parameter that affected titanium neighbors and Li migration.

We present an extended X-ray absorption fine structure study of the pyrochlores AMoO (A = Gd, Dy, Ho, Er), as a function of temperature. While in the three spin-glass compositions DyMoO, HoMoO and ErMoO the Debye temperatures are in accordance with other pyrochlores and the static disorder contributions are compatible with a lattice frustration, in the low-temperature-ferromagnetic GdMoO system we point out an anomalous enhancement of the local structure disorder below about 225 K down to low temperatures. Moreover, considering the general pyrochlore predisposition towards structural disorder, we prove the presence on a local scale of at least a bimodal distribution of the Mo-O(1) octahedral interatomic distances for all the studied compounds, consisting of two shorter and four longer bond lengths. Our results suggest that the local structure order parameter plays an important role in the ferromagnetic or spin-glass phase stabilization., F.R.-M. is also indebted to MINECO for a ‘Ramon y Cajal’ contract (ref: RyC-2015-18626), which is co-financed by the European Social Fund 2014-20.

Incorporation of rare-earth (RE) ions in the fluoride crystals of oxyfluoride glass-ceramics greatly improves the optical properties of these materials, such as the up-conversion emission. In this work, we present a study of this incorporation using X-ray absorption near-edge structure (XANES) spectroscopy and extended X-ray absorption fine structure (EXAFS) spectroscopy. Both techniques allow quantifying the distribution of these ions in the glass matrix and the fluoride crystals. We found that 27% of Tm3 + ions are incorporated in LaF3 nano-crystals. © 2013 Elsevier B.V., The authors acknowledge the financial support of FP6 Project INTERCONY, Contract No. NMP4-CT-2006-033200 and the CiCyt projectMAT2010-20459, as well as the Spanish Beamline (SpLine) at the ESRF facilities in Grenoble. A. De Pablos-Martín is grateful to CSIC for her JAE contract 2008–2011 and the FhG Internal Programs under Grant No. Attract 692 280.

A characterization study of nanoworm Au thin films fabricated onto Si (100) using an intermediate columnar porous silicon (PSi) layer is presented. The Au thin films are resistant to peeling in different buffers and solvents. Adhesion arises from the presence of a diffused Au nucleation layer in the channeled PSi, which can be observed even at short electroless Au deposition times. For longer deposition times, a gold surface film grows from piled and aggregated Au crystals, providing high surface area. X-ray absorption spectroscopy studies revealed differences in the Au L 3 absorption edge that can be ascribed to the induced nanoworm structure. The optical behavior of the Au grown on the surface has also been studied by light reflectance spectroscopy and related to the characteristic Au intra-band absorption. Such surfaces could enhance the performance of electric or optical devices with sensitivity limited by surface area availability.

Deposition of allylamine (ALL) by plasma enhanced chemical vapor deposition has been optimized on silicon based models. Simultaneous energy recoil detection analysis and Rutherford backscattering spectra show that 100 W deposition is ideal in terms of polymerized film formation and H content while, lower or higher power induce reduced film retention or excessive cross linking, respectively. Surface composition of the ALL film was further probed by X-ray photoelectron spectroscopy revealing a monocomponent N 1s spectrum compatible with the presence of primary amines. Optimized ALL films were applied to polycaprolactone (PCL) surfaces after Ar plasma activation with implications in the chemistry and wettability of this biocompatible polymer. Human mesenchymal stem cells (hMSCs) were cultured on ALL coated PCL surface and controls. ALL functionalized PCL was found to be especially attractive for the formation of confluent monolayers of hMSCs after 72 h of culture.

Polymorph minerals are natural materials that share the same composition but have a different structure. Traditionally, the characterization of polymorphs has been done using different techniques of microscopy, X-ray diffraction Raman or IR Spectroscopy for instance. In this work we propose the use of a new technique as an alternative to characterise polymorphs: Ion Beam Induced Luminescence (IBIL). As an advantage to the other techniques, IBIL can be carried out simultaneously with the PIXE technique or other Ion Beam Analysis techniques and the combination will yield results on elemental composition and luminescence properties at the same time. Different minerals have been analysed with IBIL as an example of application to the characterization of polymorphs and its correspondent spectra are explained in this paper.