scholarly journals Structural Disorder of Mechanically Activated δ-MgCl2 Studied by Synchrotron X-ray Total Scattering and Vibrational Spectroscopy

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1089
Author(s):  
Toru Wada ◽  
Ashutosh Thakur ◽  
Patchanee Chammingkwan ◽  
Minoru Terano ◽  
Toshiaki Taniike ◽  
...  
Keyword(s):  
Early Stage ◽  
Mechanical Energy ◽  
Structural Disorder ◽  
Reliable Determination ◽  
Total Scattering ◽  
X Ray ◽  
Powerful Approach ◽  
Ft Ir ◽  
Grinding Time

A combination of synchrotron X-ray total scattering and molecular simulation is a powerful approach for reliable determination of the structure of δ-MgCl2 as an indispensable component of heterogeneous Ziegler–Natta catalysts. Here, the same approach is applied to mechanically activated MgCl2. Four types of mechanically activated MgCl2 samples are prepared using ball-milling in the absence and presence of different donors. The development of structural disorder along the grinding time is compared. It was found that the presence of donors accelerates the formation of δ-MgCl2 in an early stage of grinding, while elongated grinding eventually results in δ-MgCl2 with similar extents of structural disorder in the absence and presence of different donors. The FT-IR investigation consistently verified the morphological similarity between the firmly ground samples. Thus, the structure of δ-MgCl2 is likely governed by mechanical energy when sufficiently ground.

scholarly journals Calculation of total scattering from a crystalline structural model based on experimental optics parameters

2020 ◽  
Vol 53 (3) ◽  
pp. 671-678 ◽  
Author(s):  
Satoshi Hiroi ◽  
Koji Ohara ◽  
Satoru Ohuchi ◽  
Yukihiro Umetani ◽  
Takashi Kozaki ◽  
...  
Keyword(s):  
Amorphous Materials ◽  
Structural Model ◽  
Direct Calculation ◽  
Structural Disorder ◽  
Optical Parameters ◽  
Diffraction Profile ◽  
Total Scattering ◽  
X Ray ◽  
Scattering Measurements ◽  
Total Structure

Total scattering measurements enable understanding of the structural disorder in crystalline materials by Fourier transformation of the total structure factor, S(Q), where Q is the magnitude of the scattering vector. In this work, the direct calculation of total scattering from a crystalline structural model is proposed. To calculate the total scattering intensity, a suitable Q-broadening function for the diffraction profile is needed because the intensity and the width depend on the optical parameters of the diffraction apparatus, such as the X-ray energy resolution and divergence, and the intrinsic parameters. X-ray total scattering measurements for CeO2 powder were performed at beamline BL04B2 of the SPring-8 synchrotron radiation facility in Japan for comparison with the calculated S(Q) under various optical conditions. The evaluated Q-broadening function was comparable to the full width at half-maximum of the Bragg peaks in the experimental total scattering pattern. The proposed calculation method correctly accounts for parameters with Q dependence such as the atomic form factor and resolution function, enables estimation of the total scattering factor, and facilitates determination of the reduced pair distribution function for both crystalline and amorphous materials.

Ball-Milling Stimulated Mechanochemical Processes in the System “Titanium-Toluene”

2019 ◽  
Vol 946 ◽  
pp. 351-356 ◽  
Author(s):  
Olga M. Kanunnikova ◽  
V.V. Aksenova ◽  
G.A. Dorofeev
Keyword(s):  
Ball Milling ◽  
Mechanical Energy ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Liquid Phases ◽  
Ft Ir ◽  
Titanium Powders ◽  
Solid Phases ◽  
Ft Ir Spectroscopy

The present work deals with the investigation of the transformations of the solid and liquid phases at high energy planetary ball milling of toluene together with titanium powder. The sequence of structural toluene transformations using FT-IR spectroscopy was investigated. Phase constitutions and morphology of ball milled titanium powders were studied by X-ray diffraction and scanning electron microscopy. It is shown that mechanically induced destruction of toluene occurs by the mechanism of catalytic cracking. During ball milling, concentration of aromatic hydrocarbons in the liquid phase decreases, at the same time the content of alkenes, cycloalkanes, and isoalkanes increases. The main solid products of the mechanosynthesis were cubic and hexagonal titanium carbo-hydrides.Evolution of lattice parameters, crystallites sizes, and micro-stresses of the solid phases during ball milling as a function of the mechanical energy dose have been discussed.

Ftir and Resolved Esca Studies of Segmented Polyether Polyurethanes

1985 ◽  
Vol 55 ◽  
Author(s):  
G. L. Grobe ◽  
Joseph A. Gardella ◽  
Roland L. Chin ◽  
Lawrence Salvati
Keyword(s):  
Photoelectron Spectroscopy ◽  
Domain Size ◽  
Attenuated Total Reflectance ◽  
Concentration Gradients ◽  
X Ray ◽  
Solution Cast ◽  
Ft Ir ◽  
Segmented Polyurethanes ◽  
Hildebrand Solubility Parameter

ABSTRACTSurface analysis of biomedical materials is necessary for determination of surface structure/biological property relationships. Previous studies [3,6] have demonstrated the applicability of Angle Resolved X-Ray Photoelectron Spectroscopy (ARXPS or ARESCA) and Fourier Transform Infrared Spectroscopy (FT-IR) with Attenuated Total Reflectance (ATR) sampling. Using these surface sensitive techniques on currently marketed segmented polyurethanes (SPU) (Biomer TMand Cardiothane-51TM), we have investigated chemical and morpholgical differences between polymeric mixtures cast from solvents of varying polarity. These materials are used because of their resistance to degradation and hydrolysis.Results will show: (1) Selective casting of different constituents of the mixture as monitored by FT-IR, where polymers can be represented as opposed to block copolymers; (2) Correlation between the Hildebrand solubility parameter of the casting solvent and the portion of the polymer selectively cast; (3) Models of solution cast polymers will be presented including (concentration gradient) of the constituents; (4) SEM micrographs will provide information on domain size and the formation of these solution cast films; (5) Depths and concentration gradients will be estimated by comparing results from AHXPS and variable angle FT-IR/ATR.

scholarly journals Exafs Studies of Multilayer Interfaces

1988 ◽  
Vol 143 ◽  
Author(s):  
S. M. Heald ◽  
G. M. Lamble
Keyword(s):  
Fine Structure ◽  
Standing Wave ◽  
Structural Disorder ◽  
Interface Structure ◽  
X Ray ◽  
Absorption Fine ◽  
High Degree ◽  
X Ray Absorption ◽  
Multilayer Materials

AbstractImportant for the understanding of multilayer materials is a determination of their interface structure. The extended x-ray absorption fine structure (EXAFS) technique can be useful, particularly for interfaces with a high degree of structural disorder. This paper reviews the application of EXAFS to multilayers, and describes the standing wave enhancement of the EXAFS from multilayer interfaces. Examples are given for W-C and Ni- Ti multilayers.

Determination of particle-induced structural disorder depth profile in crystals using the grazing-angle incidence hard x-ray backscattering diffraction technique

2011 ◽  
Vol 44 (49) ◽  
pp. 495102
Author(s):  
Hakob (Jacob) P Bezirganyan ◽  
Siranush E Bezirganyan ◽  
Petros H Bezirganyan ◽  
Hayk H Bezirganyan
Keyword(s):  
Depth Profile ◽  
Grazing Angle ◽  
Structural Disorder ◽  
X Ray

scholarly journals Total body water and extracellular water measurements throughin vivodilution of D2O and bromide as tracers

2003 ◽  
Vol 17 (2-3) ◽  
pp. 603-611 ◽  
Author(s):  
Giuseppe Sergi ◽  
Roberta Bertani ◽  
Irene Calliari ◽  
Lucia Lupoli ◽  
Adriano Berton ◽  
...  
Keyword(s):  
Total Body Water ◽  
Body Fluids ◽  
Body Water ◽  
Energy Dispersive ◽  
Extracellular Water ◽  
X Ray ◽  
Pathological Conditions ◽  
Ft Ir ◽  
Total Body

Large interest is into the determination of body fluids because of changes in body water in a wide variety of physiological and pathological conditions. Here methods based on dilution of tracers, are reported, for the extracellular water (ECW) and total body water (TBW) determinations on the same sample. As for ECW, bromide is used as tracer and its concentration is determined by energy dispersive X-ray spectrometry; while as for TBW, D2O is used as tracer and HOD is determined by FT IR. Both methods represent significant improvements with respect the procedures described in the literature in terms of availability, reproducibility and accuracy.

scholarly journals Multiple scattering in grazing-incidence X-ray diffraction: impact on lattice-constant determination in thin films

2016 ◽  
Vol 23 (3) ◽  
pp. 729-734 ◽  
Author(s):  
Roland Resel ◽  
Markus Bainschab ◽  
Alexander Pichler ◽  
Theo Dingemans ◽  
Clemens Simbrunner ◽  
...  
Keyword(s):  
Thin Films ◽  
Critical Angle ◽  
Grazing Incidence ◽  
X Rays ◽  
Organic Thin Film ◽  
X Ray Diffraction ◽  
Reliable Determination ◽  
X Ray ◽  
Out Of Plane

Dynamical scattering effects are observed in grazing-incidence X-ray diffraction experiments using an organic thin film of 2,2′:6′,2′′-ternaphthalene grown on oxidized silicon as substrate. Here, a splitting of all Bragg peaks in the out-of-plane direction (z-direction) has been observed, the magnitude of which depends both on the incidence angle of the primary beam and the out-of-plane angle of the scattered beam. The incident angle was varied between 0.09° and 0.25° for synchrotron radiation of 10.5 keV. This study reveals comparable intensities of the split peaks with a maximum for incidence angles close to the critical angle of total external reflection of the substrate. This observation is rationalized by two different scattering pathways resulting in diffraction peaks at different positions at the detector. In order to minimize the splitting, the data suggest either using incident angles well below the critical angle of total reflection or angles well above, which sufficiently attenuates the contributions from the second scattering path. This study highlights that the refraction of X-rays in (organic) thin films has to be corrected accordingly to allow for the determination of peak positions with sufficient accuracy. Based thereon, a reliable determination of the lattice constants becomes feasible, which is required for crystallographic structure solutions from thin films.

Comparison of FT-IR, Thermal Analysis and XRD for Determination of Products of Cement Hydration

2010 ◽  
Vol 168-170 ◽  
pp. 518-522 ◽  
Author(s):  
Zhi Hua Ou ◽  
Bao Guo Ma ◽  
Shou Wei Jian
Keyword(s):  
Thermal Analysis ◽  
Fourier Transform ◽  
Cement Hydration ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Cement Pastes ◽  
X Ray ◽  
Degree Of Hydration ◽  
Ft Ir

Fourier Transform Infrared Spectroscopy (FT-IR), thermal analysis and X-Ray Diffraction (XRD) are commonly performed to study the hydration products in cement pastes. The three methods were compared in this frame to detect products of cement hydration at different ages, especially at early ages (before 24h ages). The results indicate from the present experiment that CH (Calcium hydroxide) can be detected by three methods at all ages; C-S-H can be distinguished by FT-IR at all ages; ettringite may be detected by FT-IR before 24h ages and by XRD at all ages; and monosulphate can be detected by FT-IR before 24h ages. The process of cement hydration, characterized by formation and development of some hydration products, can be clearly observed by three methods. FT-IR is suggested for detecting the major hydration products before 24h ages, FT-IR and XRD are suggested for detecting the major hydration products after 24h ages, and thermal analysis is suggested for analyzing the degree of hydration quantitatively.

scholarly journals Local Structure of Iridate Pyrochlores from Hydrothermal Synthesis

2014 ◽  
Vol 70 (a1) ◽  
pp. C869-C869
Author(s):  
Helen Playford ◽  
Ravi SINGH ◽  
Lieh Jeng Chang ◽  
Kripasindhu Sardar ◽  
Alex Hannon ◽  
...  
Keyword(s):  
Local Structure ◽  
Synthesis Method ◽  
Pyrochlore Structure ◽  
Magnetic Ordering ◽  
Structural Disorder ◽  
Lattice Parameter ◽  
Magnetic Behaviour ◽  
Total Scattering ◽  
X Ray ◽  
Cation Content

Iridate pyrochlores of general formula M2Ir2O7have potential applications in catalysis [1]. They also often exhibit unusual magnetic and electronic properties caused by spin-orbit coupling and geometric frustration [2]. A detailed understanding of structure is necessary to enable these properties to be understood and exploited. Because of the propensity of the pyrochlore structure to accommodate structural disorder, we have chosen to utilise the technique of total scattering to examine the structure of M2Ir2O7(M = Bi, Nd). The sensitivity of our measurements to all the constituent elements is maximised by the combination of both neutron and X-ray total scattering. We find no evidence for magnetic ordering in our samples of Nd2Ir2O7, in contrast to literature reports [3]. By comparing the local structure of our samples with that of one reported to exhibit magnetic ordering, we explore the possibility of a structural origin for the differences in magnetic behaviour. We have found that synthesis method can directly influence the structure of these iridate pyrochlores. Local structural analysis provides evidences of A-site cation deficiency and partial oxidation of Ir(IV) to Ir(V) in samples produced by hydrothermal techniques. Irreversible changes to the lattice parameter upon heating these samples at 400 – 9000C further support the inference that the cation content is somewhat variable. We report the results of reverse Monte Carlo (RMC) refinements using the program RMCProfile, which is capable of simultaneously fitting to X-ray and neutron data, and therefore provides structural models of the greatest possible accuracy. We also report the results of in situ X-ray total scattering measurements which provide local-scale insight into the interesting thermal behaviour and apparent flexible cation content of these materials.

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