scholarly journals Synchrotron microanalytical methods in the study of trace and minor elements in apatite

Mineralogia ◽  
2008 ◽  
Vol 39 (1-2) ◽  
pp. 31-40 ◽  
Author(s):  
John Rakovan ◽  
Yun Luo ◽  
Olaf Borkiewicz
Keyword(s):  
Analytical Techniques ◽  
Photon Flux ◽  
High Temporal Resolution ◽  
Phase Identification ◽  
X Ray Diffraction ◽  
Edge Structure ◽  
X Ray ◽  
Minor Elements ◽  
Trace And Minor Elements ◽  
X Ray Absorption

Synchrotron microanalytical methods in the study of trace and minor elements in apatiteSynchrotron X-ray facilities have the capability for numerous microanalytical methods with spatial resolutions in the micron to submicron range and sensitivities as low as ppm to ppb. These capabilities are the result of a high X-ray brilliance (many orders of magnitude greater than standard tube and rotating anode sources); a continuous, or white, spectrum through the hard X-ray region; high degrees of X-ray columniation and polarization; and new developments in X-ray focusing methods. The high photon flux and pulsed nature of the source also allow for rapid data collection and high temporal resolution in certain experiments. Of particular interest to geoscientists are X-ray fluorescence microprobes which allow for numerous analytical techniques including X-ray fluorescence (XRF) analysis of trace element concentrations and distributions; X-ray absorption spectroscopy (XAS) for chemical speciation, structural and oxidation state information; X-ray diffraction (XRD) for phase identification; and fluorescence microtomography (CMT) for mapping the internal structure of porous or composite materials as well as elemental distributions (Newville et al. 1999; Sutton et al. 2002; Sutton et al. 2004).We have employed several synchrotron based microanalytical methods including XRF, microEXAFS (Extended X-ray Absorption Fine Structure), microXANES (X-ray Absorption Near Edge Structure) and CMT for the study of minor and trace elements in apatite (and other minerals). We have also been conducting time resolved X-ray diffraction to study nucleation of and phase transformations among precursor phases in the formation of apatite from solution at earth surface conditions. Summaries of these studies are given to exemplify the capabilities of synchrotron microanalytical techniques.

Material Characteristics and Electrical Modeling of Ultra Thin Copper Oxides in ULSI Application

2007 ◽  
Vol 561-565 ◽  
pp. 1225-1228
Author(s):  
Takayuki Ohba
Keyword(s):  
Diffraction Pattern ◽  
Barrier Height ◽  
Oxide Thickness ◽  
Amorphous Structure ◽  
Emission Model ◽  
X Ray Diffraction ◽  
Edge Structure ◽  
X Ray ◽  
Current Emission ◽  
X Ray Absorption

With the highest brilliance synchrotron radiation X-ray (SPring-8) and TEM observations, Cu oxides ranged 2-nm to 10-nm in thickness formed on sputtered Cu has been evaluated. For the plasma-assisted Cu oxide, weak Cu2O and/or CuO X-ray diffraction pattern is observed, while no diffraction pattern in native and thermally (170°C) grown oxides. Those native and thermal oxides show Cu2O coordination observed by XANES (X-ray Absorption Near Edge Structure) method. This suggests that Cu oxide formed at low temperatures consists of stoichiometric Cu2O in an amorphous structure. According to the Fowler-Nordheim (F-N) current emission model, the current emission taking place at Cu2O decreases with increasing of the oxide thickness and its mean barrier height (φB) in the MIM band structure. In case of current density at 106A/cm2 of 1V, it is estimated that the allowable thickness of Cu oxides is approximately 1.5-nm at 1 eV of barrier height.

scholarly journals The Atomic-Scale Interaction of Bioactive Glasses with Simulated Body Fluid

2005 ◽  
Vol 480-481 ◽  
pp. 21-26 ◽  
Author(s):  
L.J. Skipper ◽  
F.E. Sowrey ◽  
D.M. Pickup ◽  
R.J. Newport ◽  
K.O. Drake ◽  
...  
Keyword(s):  
Simulated Body Fluid ◽  
Body Fluid ◽  
Sol Gel ◽  
Atomic Scale ◽  
X Ray Diffraction ◽  
Bioactive Glasses ◽  
Edge Structure ◽  
X Ray ◽  
X Ray Absorption

The formation of a carbonate-containing hydroxyapatite, HCAp, layer on bioactive calcium silicate sol-gel glass of the formula (CaO)0.3(SiO2)0.7 has been studied in-vitro in Simulated Body Fluid (SBF). Extended X-ray Absorption Fine Structure (EXAFS), X-ray Absorption Near Edge Structure (XANES), X-ray diffraction (XRD), and solid state nuclear magnetic resonance (NMR) measurements have been performed with results showing the formation of a significantly amorphous HCAp layer after less than 5 hours in solution.

scholarly journals The nature and effects of rhodium and antimony dopants on the electronic structure of TiO2: towards design of Z-scheme photocatalysts

2016 ◽  
Vol 4 (18) ◽  
pp. 6946-6954 ◽  
Author(s):  
E. N. K. Glover ◽  
S. G. Ellington ◽  
G. Sankar ◽  
R. G. Palgrave
Keyword(s):  
Fine Structure ◽  
Photoelectron Spectroscopy ◽  
Diffuse Reflectance ◽  
Diffuse Reflectance Spectroscopy ◽  
Reflectance Spectroscopy ◽  
X Ray Diffraction ◽  
Edge Structure ◽  
X Ray ◽  
Antimony Doping ◽  
X Ray Absorption

The nature and effects of rhodium and antimony doping in TiO2 have been investigated using X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Extended X-ray Absorption Fine Structure (EXAFS), X-ray Absorption Near Edge Structure (XANES) and diffuse reflectance spectroscopy.

Simple Preparation of Cuprous Oxide Nanoparticles for Catalysis of Azide–alkyne Cycloaddition

2018 ◽  
Vol 42 (3) ◽  
pp. 166-169 ◽  
Author(s):  
Mojtaba Amini ◽  
Sakine Ramezani ◽  
Alireza Pourvahabi Anbari ◽  
Abolghasem Beheshti ◽  
Sanjeev Gautam ◽  
...  
Keyword(s):  
Cuprous Oxide ◽  
Benzyl Chloride ◽  
Significant Loss ◽  
Oxide Nanoparticles ◽  
X Ray Diffraction ◽  
Edge Structure ◽  
X Ray ◽  
Organic Azides ◽  
Cuprous Oxide Nanoparticles ◽  
X Ray Absorption

Cuprous oxide (Cu2O) nanoparticles were prepared by two simple methods and their structural, morphological and electronic properties were investigated by X-ray diffraction analysis, X-ray absorption near-edge structure, energy dispersive X-ray analysis and scanning electron microscopy. Cuprous oxide nanoparticles efficiently catalyse 1,3-dipolar cycloaddition of a variety terminal alkynes and organic azides producing the corresponding 1,2,3-triazole derivatives in excellent yields without use of any additives. Phenylacetylene and benzyl chloride were chosen as model starting compounds for the optimisation of the reaction conditions, such as effect of solvent, reaction temperature and time of reaction in the presence of a-Cu2O nanoparticles as a catalyst. The results showed that using cuprous oxide nanoparticles (0.035 mmol) and heating at 70 °C in water, the reaction of phenylacetylene with benzyl chloride and sodium azide gave 1-benzyl-4-phenyl-1 H-1,2,3-triazole almost quantitatively in 6 h of reaction time. A study of the recyclability and reusability of the catalyst revealed that a-Cu2O could be reused at least five times without significant loss of yield.

The Structural Characterization of a Series of Uranium-containing Gadolinium Zirconates

2012 ◽  
Vol 1475 ◽  
Author(s):  
Daniel J. Gregg ◽  
Yingjie Zhang ◽  
Zhaoming Zhang ◽  
Inna Karatchevtseva ◽  
Mark G. Blackford ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Diffuse Reflectance ◽  
Charge Balance ◽  
X Ray Diffraction ◽  
Edge Structure ◽  
Gadolinium Zirconate ◽  
X Ray ◽  
Host Materials ◽  
X Ray Absorption

ABSTRACTA series of uranium-containing gadolinium zirconate samples have been fabricated at 1723 K in air. X-ray diffraction and Raman spectroscopy have confirmed pyrochlore or defect fluorite structures, while diffuse reflectance, X-ray absorption near edge structure and X-ray photoelectron spectroscopies indicate a predominantly U6+ oxidation state, even when Ca2+ was added to charge balance for U4+. The results demonstrate the potential of gadolinium zirconates as host materials for actinides.

Crystalline Phases and Electronic Structures in Superconducting Bi – Sr – Ca – Cu Oxides

1997 ◽  
Vol 12 (8) ◽  
pp. 2009-2013
Author(s):  
M. D. Giardina ◽  
R. Feduzi ◽  
D. Inzaghi ◽  
A. Manara ◽  
C. Giori ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Photoelectron Spectroscopy ◽  
Electronic Structures ◽  
Theoretical Interpretation ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Edge Structure ◽  
X Ray ◽  
Quantum Percolation ◽  
X Ray Absorption

Two classes of samples, designated A and B, of layered Bi–Sr–Ca–Cu oxides having the same nominal composition 4 : 3 : 3 : 4, but different thermal histories, were investigated by using field modulated microwave absorption (ESR), powder x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and x-ray absorption near the edge structure (XANES). Previous electrical resistivity measurements showed that the B samples presented only two superconducting phases with midpoints of the transition temperatures at ∼80 K and ∼105 K. The microwave absorption technique indicated instead the presence of islands which became superconducting at the above-mentioned temperatures also in the A samples. The crystalline and electronic structures of the two types of samples are illustrated and discussed. A plausible theoretical interpretation of the experimental results, based on a quantum percolation model with Coulomb interaction, is also given.

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