scholarly journals Generating Mechanism of Catalytic Effect for Hydrogen Absorption/Desorption Reactions in NaAlH4–TiCl3

2021 ◽  
Vol 11 (18) ◽  
pp. 8349
Author(s):  
Kazutaka Ikeda ◽  
Fumika Fujisaki ◽  
Toshiya Otomo ◽  
Hidetoshi Ohshita ◽  
Takashi Honda ◽  
...  
Keyword(s):  
Catalytic Effect ◽  
Catalytic Mechanism ◽  
Hydrogen Desorption ◽  
Ti Alloy ◽  
X Ray Diffraction ◽  
Desorption Process ◽  
Rietveld Refinements ◽  
X Ray ◽  
X Ray Scattering ◽  
X Ray Absorption

The hydrogen desorption and absorption reactions of the complex metal hydride NaAlH4 are disproportionation processes, and the kinetics can be improved by adding a few mol% of Ti compounds, although the catalytic mechanism, including the location and state of Ti, remains unknown. In this study, we aimed to reveal the generating mechanism of catalytic Al–Ti alloy in NaAlH4 with TiCl3 using quantum multiprobe techniques such as neutron diffraction (ND), synchrotron X-ray diffraction (XRD), anomalous X-ray scattering (AXS), and X-ray absorption fine structure (XAFS). Rietveld refinements of the ND and XRD, profiles before the first desorption of NaAlD(H)4–0.02TiCl3 showed that Al in NaAlD(H)4 was partially substituted by Ti. On the other hand, Ti was not present in NaAlH4, and Al–Ti nanoparticles were detected in the XRD profile after the first re-absorption. This was consistent with the AXS and XAFS results. It is suggested that the substitution promotes the formation of a highly dispersed nanosized Al–Ti alloy during the first desorption process and that the effectiveness of TiCl3 as an additive can be attributed to the dispersion of Ti.

Confocal X-ray technology based on capillary X-ray optics

2015 ◽  
Vol 34 (1-2) ◽  
Author(s):  
Tianxi Sun ◽  
Xunliang Ding
Keyword(s):  
Life Science ◽  
Food Science ◽  
X Ray Diffraction ◽  
Ray Optics ◽  
X Ray ◽  
X Ray Scattering ◽  
X Ray Imaging ◽  
X Ray Absorption ◽  
Security Check ◽  
Ray Scattering

AbstractCapillary X-ray optics is versatile, and it can be used with synchrotron radiation source, conventional X-ray source, laser-plasma ultrafast X-ray source, and so forth. Recently, the confocal X-ray technology based on capillary X-ray optics has become popular, and it has been widely used in X-ray fluorescence, X-ray absorption fine structure, X-ray diffraction, small-angle X-ray scattering, X-ray imaging, and X-ray scattering. This confocal X-ray technology has applications in many fields, including environmental monitoring, food science, life science, chemistry, physics, nanomaterials, nondestructive test, security check, and so on.

In Situ X-ray Absorption Spectroscopy–X-ray Diffraction Investigation of Nb–H Nanoclusters in MgH2 during Hydrogen Desorption

2015 ◽  
Vol 119 (14) ◽  
pp. 7765-7770 ◽  
Author(s):  
C. Maurizio ◽  
R. Checchetto ◽  
A. Trapananti ◽  
A. Rizzo ◽  
F. D’Acapito ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Hydrogen Desorption ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Absorption

XDS: a flexible beamline for X-ray diffraction and spectroscopy at the Brazilian synchrotron

2016 ◽  
Vol 23 (6) ◽  
pp. 1538-1549 ◽  
Author(s):  
F. A. Lima ◽  
M. E. Saleta ◽  
R. J. S. Pagliuca ◽  
M. A. Eleotério ◽  
R. D. Reis ◽  
...  
Keyword(s):  
High Pressures ◽  
Materials Science ◽  
Photon Flux ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Science Community ◽  
Synchrotron Light ◽  
X Ray Absorption ◽  
Photon Source

The majority of the beamlines at the Brazilian Synchrotron Light Source Laboratory (LNLS) use radiation produced in the storage-ring bending magnets and are therefore currently limited in the flux that can be used in the harder part of the X-ray spectrum (above ∼10 keV). A 4 T superconducting multipolar wiggler (SCW) was recently installed at LNLS in order to improve the photon flux above 10 keV and fulfill the demands set by the materials science community. A new multi-purpose beamline was then installed at the LNLS using the SCW as a photon source. The XDS is a flexible beamline operating in the energy range between 5 and 30 keV, designed to perform experiments using absorption, diffraction and scattering techniques. Most of the work performed at the XDS beamline concentrates on X-ray absorption spectroscopy at energies above 18 keV and high-resolution diffraction experiments. More recently, new setups and photon-hungry experiments such as total X-ray scattering, X-ray diffraction under high pressures, resonant X-ray emission spectroscopy, among others, have started to become routine at XDS. Here, the XDS beamline characteristics, performance and a few new experimental possibilities are described.

scholarly journals The crystal structure of compositionally homogeneous mixed ceria-zirconia oxides by high resolution X-ray and neutron diffraction methods

2017 ◽  
Vol 15 (1) ◽  
pp. 438-445 ◽  
Author(s):  
Alexander N. Shmakov ◽  
Svetlana V. Cherepanova ◽  
Dmitrii A. Zyuzin ◽  
Yulia E. Fedorova ◽  
Ivan A. Bobrikov ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Single Phase ◽  
Mixed Oxides ◽  
Homogeneous Distribution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxygen Interstitial ◽  
X Ray Scattering ◽  
Anion Vacancies ◽  
X Ray Absorption

AbstractThe real/atomic structure of single phase homogeneous nanocrystalline Ce0.5Zr0.5O2±δoxides prepared by a modified Pechini route and Ni-loaded catalysts of methane dry reforming on their bases was studied by a combination of neutron diffraction, synchrotron X-ray diffraction, total X-ray scattering and X-ray absorption spectroscopy. The effects of sintering temperature and pretreatment in H2were elucidated. The structure of the mixed oxides corresponds to a tetragonal space group indicating a homogeneous distribution of Ce and Zr cations in the lattice. A pronounced disordering of the oxygen sublattice was revealed by neutron diffraction, supposedly due to incorporation of water into the structure when in contact with air promoted by the generation of anion vacancies in the lattice after reduction or calcination at high temperatures. However, such disordering has not resulted in any occupation of the oxygen interstitial positions in the bulk of the nanodomains.

scholarly journals Synchrotron Radiation Based Study of the Catalytic Mechanism of Ag+ to Chalcopyrite Bioleaching by Mesophilic and Thermophilic Cultures

Minerals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 382 ◽  
Author(s):  
Zhenyuan Nie ◽  
Weiwei Zhang ◽  
Hongchang Liu ◽  
Jinlan Xia ◽  
Wei Zhu ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Catalytic Mechanism ◽  
Copper Extraction ◽  
X Ray Diffraction ◽  
Edge Structure ◽  
Secondary Minerals ◽  
X Ray ◽  
Catalytic Mechanisms ◽  
X Ray Absorption ◽  
Insight Into

The catalytic mechanism of Ag+ for chalcopyrite bioleaching by mesophilic culture (at 30 °C) and thermophilic culture (at 48 °C) was investigated using synchrotron radiation-based X-ray diffraction (SR-XRD) and S K-edge and Fe L-edge X-ray absorption near edge structure (XANES) spectroscopy. Bioleaching experiments showed that copper extraction from chalcopyrite bioleaching by both cultures was promoted significantly by Ag+, with more serious corrosion occurring on the minerals surface. SR-XRD and XANES analyses showed that the intermediates S0, jarosite and secondary minerals (bornite, chalcocite and covellite) formed for all bioleaching experiments. For these secondary minerals, the formation of bornite and covellite was promoted significantly in the presence of Ag+ for both cultures, while Ag+ has almost no effect on the formation of chalcocite. These results provided insight into the catalytic mechanisms of Ag+ to chalcopyrite bioleaching by the mesophilic and thermophilic cultures, which are both probably due to the rapid formation of bornite by Ag+ and the conversion of bornite to covellite.

Differential anomalous wide-angle X-ray scattering and X-ray absorption experiments to investigate the formation of glass ceramics in the CaO–SiO2–ZrO2system

1999 ◽  
Vol 32 (6) ◽  
pp. 1090-1099 ◽  
Author(s):  
Carlo Meneghini ◽  
Alessandro F. Gualtieri ◽  
Cristina Siligardi
Keyword(s):  
Glass Ceramic ◽  
Room Temperature ◽  
Glass Ceramics ◽  
Anomalous Scattering ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Two Samples ◽  
Devitrification Process ◽  
X Ray Absorption

The structure of a CaO–SiO2–ZrO2-based glass ceramic has been investigated by X-ray diffraction, X-ray absorption spectroscopy and differential anomalous scattering techniques as a function of the thermal treatment of the sample. The microstructure of the glass has been investigated at room temperature, before the recrystallization of the glass ceramic, and on two samples annealed at 1073 and 1273 K for 1 h to follow the early stages of nucleation of the quartz and wollastonite crystalline phases. Indications on the roles of Ca, Si and Zr during the devitrification process are given.

New Structure of CTAB Templated Silica Films as revealed by GISAXS coupled to HRTEM

2000 ◽  
Vol 628 ◽  
Author(s):  
Sophie Besson ◽  
Catherine Jacquiod ◽  
Thierry Gacoin ◽  
André Naudon ◽  
Christian Ricolleau ◽  
...  
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Grazing Incidence ◽  
Hexagonal Structure ◽  
X Ray Diffraction ◽  
Electronic Microscopy ◽  
Silica Films ◽  
X Ray ◽  
X Ray Scattering ◽  
Hexagonal Arrangement ◽  
Spherical Micelles

ABSTRACTA microstructural study on surfactant templated silica films is performed by coupling traditional X-Ray Diffraction (XRD) and Transmission Electronic Microscopy (TEM) to Grazing Incidence Small Angle X-Ray Scattering (GISAXS). By this method it is shown that spin-coating of silicate solutions with cationic surfactant cetyltrimethylammonium bromide (CTAB) as a templating agent provides 3D hexagonal structure (space group P63/mmc) that is no longer compatible with the often described hexagonal arrangement of tubular micelles but rather with an hexagonal arrangement of spherical micelles. The extent of the hexagonal ordering and the texture can be optimized in films by varying the composition of the solution.

scholarly journals X-ray and Neutron Study on the Structure of Hydrous SiO2 Glass up to 10 GPa

Minerals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 84 ◽  
Author(s):  
Satoru Urakawa ◽  
Toru Inoue ◽  
Takanori Hattori ◽  
Asami Sano-Furukawa ◽  
Shinji Kohara ◽  
...  
Keyword(s):  
Oxide Glasses ◽  
Void Space ◽  
X Ray Diffraction ◽  
Amorphous Sio2 ◽  
Sio2 Glass ◽  
X Ray ◽  
X Ray Scattering ◽  
Medium Range ◽  
Two Phases ◽  
A Minor

The structure of hydrous amorphous SiO2 is fundamental in order to investigate the effects of water on the physicochemical properties of oxide glasses and magma. The hydrous SiO2 glass with 13 wt.% D2O was synthesized under high-pressure and high-temperature conditions and its structure was investigated by small angle X-ray scattering, X-ray diffraction, and neutron diffraction experiments at pressures of up to 10 GPa and room temperature. This hydrous glass is separated into two phases: a major phase rich in SiO2 and a minor phase rich in D2O molecules distributed as small domains with dimensions of less than 100 Å. Medium-range order of the hydrous glass shrinks compared to the anhydrous SiO2 glass by disruption of SiO4 linkage due to the formation of Si–OD deuterioxyl, while the response of its structure to pressure is almost the same as that of the anhydrous SiO2 glass. Most of D2O molecules are in the small domains and hardly penetrate into the void space in the ring consisting of SiO4 tetrahedra.

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