scholarly journals X-ray Laue Microdiffraction and Raman Spectroscopic Investigation of Natural Silicon and Moissanite

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 204
Author(s):  
Camelia Veronica Stan ◽  
Earl Francis O’Bannon ◽  
Pavel Mukhin ◽  
Nobumichi Tamura ◽  
Larissa Dobrzhinetskaya
Keyword(s):  
Raman Spectroscopy ◽  
Crystal Size ◽  
Accessory Mineral ◽  
Low Oxygen ◽  
Large Crystal ◽  
Continuous Growth ◽  
X Ray ◽  
Raman Spectroscopic ◽  
Low Distortion ◽  
Laue Microdiffraction

Moissanite, SiC, is an uncommon accessory mineral that forms under low oxygen fugacity. Here, we analyze natural SiC from a Miocene tuff-sandstone using synchrotron Laue microdiffraction and Raman spectroscopy, in order to better understand the SiC phases and formation physics. The studied crystals of SiC consist of 4H- and 6H-SiC domains, formed from either, continuous growth or, in one case, intergrown, together with native Si. The native Si is polycrystalline, with a large crystal size relative to the analytical beam dimensions (>1–2 μm). We find that the intergrown region shows low distortion or dislocation density in SiC, but these features are comparatively high in Si. The distortion/deformation observed in Si may have been caused by a mismatch in the coefficients of thermal expansion of the two materials. Raman spectroscopic measurements are discussed in combination with our Laue microdiffraction results. Our results suggest that these SiC grains likely grew from an igneous melt.

Dehydrogenation and Polymerization of TiOxHy Films in Obtaining Anatase Coating at Low Temperature

2002 ◽  
Vol 749 ◽  
Author(s):  
Kouichi Takayama ◽  
Shigeo Ohshio ◽  
Hidetoshi Saitoh
Keyword(s):  
Raman Spectroscopy ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Low Temperature ◽  
Vapor Deposition ◽  
Crystal Size ◽  
Chemical Vapor ◽  
Amorphous Films ◽  
X Ray ◽  
Titanium Tetra Isopropoxide

ABSTRACTChemical-vapor-deposition of titanium tetra-isopropoxide (TTIP) under the atmosphere at low temperature has been conducted. The structure of the obtained films was assessed using Fourier transform infrared spectroscopy, X-ray diffractometry and Raman spectroscopy. These analyses indicated that amorphous TiOxHy films were obtained at gas temperatures in the range of 150–300 °C, and crystalline anatase-TiO2 film was formed at 350 °C. This distinction is accounted for by plausible chemical reactions as follows; the hydroxyl reaction of TTIP below 350 °C promotes the formation of the amorphous TiOxHy. As the temperature goes up to 350 °C, dehydrogenation of the TiOxHy films promotes to form crystalline TiO2. Also the obtained amorphous films were annealed for 10 min under the atmosphere in assessing the transformation proceeding in the solid state. The structural change is shown at 350 °C, indicating that the crystalline phase would be formed via dehydrogenation and polymerization on the surface of the amorphous phase under the atmosphere. The crystal size of the annealed films was evaluated in assessment for the transformation.

What is the best crystal size for collection of X-ray data? Refinement of the structure of glycyl-L-serine based on data from a very large crystal

1999 ◽  
Vol 55 (6) ◽  
pp. 1090-1098 ◽  
Author(s):  
Carl Henrik Görbitz
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Crystal Size ◽  
Additional Data ◽  
Data Sets ◽  
Large Specimen ◽  
Large Crystal ◽  
Data Set ◽  
X Ray ◽  
Absorption Correction

The dipeptide Gly-L-Ser was crystallized as part of a study on hydrogen-bonding patterns in the structures of dipeptides. Hydrogen-bond donors and acceptors have been assigned ranks (1 is best, 2 is next best etc.), and the observed hydrogen-bond connectivity is compared with the hypothetical pattern in which the rank n donor associates with the rank n acceptor (n = 1, 2, . . .), and with the pattern observed in the retroanalogue L-Ser-Gly, which contains the same functional groups. Crystallization of the title compound produced very bulky crystals. Rather than reducing the size of one of these before data collection, three data sets with different exposure times were collected with a Siemens SMART CCD diffractometer on a very large specimen (2.2 × 2.0 × 0.8 mm). The crystal was subsequently shaped into a 0.30 mm-diameter sphere for collection of two additional data sets. The discussion of the refinement results focus on the effect of absorption correction for the various data sets, and a comparison of geometrical and thermal parameters. One advantage of using a large crystal, the great speed with which data can be obtained, has been exemplified by collection of a complete data set of good quality in less than 25 min.

Identification of mixite minerals – an SEM and Raman spectroscopic analysis

2005 ◽  
Vol 69 (2) ◽  
pp. 169-177 ◽  
Author(s):  
R. L. Frost ◽  
M. Weier ◽  
W. Martens ◽  
L. Duong
Keyword(s):  
Raman Spectroscopy ◽  
Spectroscopic Analysis ◽  
Sem Images ◽  
X Ray ◽  
Raman Spectroscopic ◽  
Bending Mode ◽  
Edx Analyses ◽  
Stretching Vibrations ◽  
Bending Modes ◽  
Raman Spectroscopic Analysis

AbstractTwo mixites from Boss Tweed Mine, Tintic District, Juab County, Utah and Tin Stope, Majuba Hill, Pershing County, Nevada, USA, were analysed by scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and by Raman spectroscopy. The SEM images show the mixite crystals to be elongated fibres up to 200 μm long and 2 μm wide. Detailed images of the mixite crystals show the mineral to be composed of bundles of fibres. The EDX analyses depend on the crystal studied, though the Majuba mixite gave analyses which matched the formula BiCu6(AsO4)3(OH)6.3H2O. Raman bands observed in the 880–910 cm−1 and 867–870 cm−1 regions are assigned to the AsO-stretching vibrations of (HAsO4)2− and (H2AsO4)− units, whilst bands at 803 and 833 cm−1 are assigned to the stretching vibrations of uncomplexed (AsO4)3- units. Intense bands observed at 473.7 and 475.4 cm−1 are assigned to the v4 bending mode of AsO4 units. Bands observed at 386.5, 395.3 and 423.1 cm−1 are assigned to the v2 bending modes of the HAsO4 (434 and 400 cm−1) and the AsO4 groups (324 cm−1). Raman spectroscopy lends itself to the identification of minerals on host matrices and is especially useful for the identification of mixites.

An X-ray Photoelectron (ESCA) and Laser Raman Spectroscopic Investigation of Aluminum Perrhenate

1980 ◽  
Vol 34 (6) ◽  
pp. 624-626 ◽  
Author(s):  
Lawrence Salvati ◽  
Gerald L. Jones ◽  
David M. Hercules
Keyword(s):  
Raman Spectroscopy ◽  
Photoelectron Spectroscopy ◽  
Heterogeneous Catalysts ◽  
Laser Raman Spectroscopy ◽  
Compound Formation ◽  
Reduction Behavior ◽  
X Ray ◽  
Raman Spectroscopic ◽  
Laser Raman ◽  
Significant Interest

Compound formation in supported heterogeneous catalysts is an area of significant interest. In the present study, Al(ReO4)3 was prepared and characterized by x-ray photoelectron spectroscopy and laser Raman spectroscopy. Characteristic spectra for Al(ReO4)3 are shown and compared to several rhenium reference compounds. The reduction behavior of Al(ReO4)3 is also explored; it was completely reduced to elemental rhenium in H2 at 500°C.

scholarly journals Raman Spectroscopic Analysis of Fingernail Clippings Can Help Differentiate between Postmenopausal Women who Have and Have Not Suffered a Fracture

2016 ◽  
Vol 9 ◽  
pp. CMAMD.S38493 ◽  
Author(s):  
James R. Beattie ◽  
Niamh M. Cummins ◽  
Clare Caraher ◽  
Olive M. O'Driscoll ◽  
Aruna T. Bansal ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Fragility Fracture ◽  
Spectroscopic Analysis ◽  
Area Under The Curve ◽  
Prediction Algorithm ◽  
X Ray ◽  
Raman Spectroscopic ◽  
T Score ◽  
Validation Set ◽  
Using Data

Raman spectroscopy was applied to nail clippings from 633 postmenopausal British and Irish women, from six clinical sites, of whom 42% had experienced a fragility fracture. The objective was to build a prediction algorithm for fracture using data from four sites (known as the calibration set) and test its performance using data from the other two sites (known as the validation set). Results from the validation set showed that a novel algorithm, combining spectroscopy data with clinical data, provided area under the curve (AUC) of 74% compared to an AUC of 60% from a reduced QFracture score (a clinically accepted risk calculator) and 61% from the dual-energy X-ray absorptiometry T-score, which is in current use for the diagnosis of osteoporosis. Raman spectroscopy should be investigated further as a noninvasive tool for the early detection of enhanced risk of fragility fracture.

The role of phlogopite in the deep Earth’s water and fluorine cycles

2020 ◽  
Author(s):  
Jiaqi Sun ◽  
Yan Yang ◽  
Qunke Xia
Keyword(s):  
Raman Spectroscopy ◽  
High Temperature ◽  
Powder Diffraction ◽  
Experimental Studies ◽  
Accessory Mineral ◽  
X Ray ◽  
Deep Earth ◽  
The Stability

<p>    Knowledge of the volatiles cycles is vital to understand the evolution of the planet Earth and the life it supports. Although it is gradually accepted that water and other volatiles are recycled into the mantle through subduction, it is still not unclear how these volatiles are transported down into the deep Earth. Phlogopite is an accessory mineral frequently observed in samples from the upper mantle, thereby acting as an important carrier of fluorine and water down to >200 km depth. Previous experimental studies and textural relationships of natural samples have indicated that fluorine-rich phlogopite can be stable under ultra-high-temperature conditions. To further investigate effects of fluorine on the stability of phlogopite, here, we present an atomic level research of effects of fluorine on the structural stability using in situ high temperature infrared spectroscopy, Raman spectroscopy, and X-ray powder diffraction. Both X-ray powder diffraction and Raman spectroscopy suggests that fluorine-poor phlogopite decomposes earlier than the fluorine-rich phlogopite. Moreover, the O-H bonds and lattice modes are stiffer for the fluorine-rich phlogopite than the fluorine-poor phlogopite, which is well responsible for the mechanism of fluorine stabilizing phlogopite. Based on our studies, we propose that fluorine-rich phlogopite can effectively transport water and fluorine to the deep Earth.</p>

Raman spectroscopy and X-ray diffraction of lithium niobate at temperatures up to 1300○-4.80pt○C

2005 ◽  
Vol 126 ◽  
pp. 101-105 ◽  
Author(s):  
B. Moulin ◽  
L. Hennet ◽  
D. Thiaudière ◽  
P. Melin ◽  
P. Simon
Keyword(s):  
Raman Spectroscopy ◽  
Lithium Niobate ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals In-situ characterization of highly reversible phase transformation by synchrotron X-ray Laue microdiffraction

2016 ◽  
Vol 108 (21) ◽  
pp. 211902 ◽  
Author(s):  
Xian Chen ◽  
Nobumichi Tamura ◽  
Alastair MacDowell ◽  
Richard D. James
Keyword(s):  
Phase Transformation ◽  
In Situ Characterization ◽  
X Ray ◽  
Reversible Phase ◽  
Laue Microdiffraction

scholarly journals Study on the Electrical, Structural, Chemical and Optical Properties of PVD Ta(N) Films Deposited with Different N2 Flow Rates

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 937
Author(s):  
Yingying Hu ◽  
Md Rasadujjaman ◽  
Yanrong Wang ◽  
Jing Zhang ◽  
Jiang Yan ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Photoelectron Spectroscopy ◽  
Crystal Size ◽  
Silicon Substrates ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
Flow Rates ◽  
X Ray ◽  
N2 Flow Rate

By reactive DC magnetron sputtering from a pure Ta target onto silicon substrates, Ta(N) films were prepared with different N2 flow rates of 0, 12, 17, 25, 38, and 58 sccm. The effects of N2 flow rate on the electrical properties, crystal structure, elemental composition, and optical properties of Ta(N) were studied. These properties were characterized by the four-probe method, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry (SE). Results show that the deposition rate decreases with an increase of N2 flows. Furthermore, as resistivity increases, the crystal size decreases, the crystal structure transitions from β-Ta to TaN(111), and finally becomes the N-rich phase Ta3N5(130, 040). Studying the optical properties, it is found that there are differences in the refractive index (n) and extinction coefficient (k) of Ta(N) with different thicknesses and different N2 flow rates, depending on the crystal size and crystal phase structure.

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