Probing atomic positions of adsorbed ammonia molecules in zeolite

2016 ◽  
Vol 52 (16) ◽  
pp. 3422-3425 ◽  
Author(s):  
Lin Ye ◽  
Benedict T.W. Lo ◽  
Jin Qu ◽  
Ian Wilkinson ◽  
Tim Hughes ◽  
...  
Keyword(s):  
X Ray Diffraction ◽  
Guest Molecules ◽  
X Ray ◽  
Adsorbed Ammonia ◽  
Experimental Errors ◽  
Zeolite P ◽  
First Time ◽  
Microporous Solids

The atomic positions and interactions between adsorbed guest molecules, such as ammonia in H-ZSM-5 microporous solids, are for the first time revealed by using in situ synchrotron powder X-ray diffraction combined with refinement within experimental errors.

scholarly journals Inclusion complexes of 2-methoxyestradiol with dimethylated and permethylated β-cyclodextrins: models for cyclodextrin–steroid interaction

2015 ◽  
Vol 11 ◽  
pp. 2616-2630 ◽  
Author(s):  
Mino R Caira ◽  
Susan A Bourne ◽  
Halima Samsodien ◽  
Vincent J Smith
Keyword(s):  
Inclusion Complexes ◽  
Anticancer Agent ◽  
Inclusion Complexation ◽  
Aqueous Solubility ◽  
X Ray Diffraction ◽  
Guest Molecules ◽  
X Ray ◽  
Rapid Dissolution ◽  
First Time ◽  
Secondary Side

The interaction between the potent anticancer agent 2-methoxyestradiol (2ME) and a series of cyclodextrins (CDs) was investigated in the solid state using thermal analysis and X-ray diffraction, while the possibility of enhancing its poor aqueous solubility with CDs was probed by means of equilibrium solubility and dissolution rate measurements. Single crystal X-ray diffraction studies of the inclusion complexes between 2ME and the derivatised cyclodextrins heptakis(2,6-di-O-methyl)-β-CD (DIMEB) and heptakis(2,3,6-tri-O-methyl)-β-CD (TRIMEB) revealed for the first time the nature of the encapsulation of a bioactive steroid by representative CD host molecules. Inclusion complexation invariably involves insertion of the D-ring of 2ME from the secondary side of each CD molecule, with the 17-OH group generally hydrogen bonding to a host glycosidic oxygen atom within the CD cavity, while the A-ring and part of the B-ring of 2ME protrude from the secondary side. In the case of the TRIMEB·2ME complex, there is evidence that complexation proceeds with mutual conformational adaptation of host and guest molecules. The aqueous solubility of 2ME was significantly enhanced by CDs, with DIMEB, TRIMEB, randomly methylated β-CD and hydroxypropyl-β-CD being the most effective hosts. The 2:1 host–guest β-CD inclusion complex, prepared by two methods, yielded very rapid dissolution in water at 37 °C relative to untreated 2ME, attaining complete dissolution within 15 minutes (co-precipitated complex) and 45 minutes (complex from kneading).

Oxygen-Induced Reversible Structural Change of Supported fine Silver Particles Observed by In Situ Optical Absorption and X-ray Diffraction

1990 ◽  
Vol 195 ◽  
Author(s):  
Akihisa Yanase ◽  
Hiroshi Komiyama ◽  
Kazunobu Tanaka
Keyword(s):  
Optical Absorption ◽  
Surface Stress ◽  
Lattice Parameter ◽  
Silver Particles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ambient Gases ◽  
First Time ◽  
Shape Of Particles

ABSTRACTIn situ measurements of optical absorption and x-ray diffraction for small supported silver particles were performed under defined atmospheres at temperatures below 723 K. We found, for the first time, reversible changes both in optical absorption spectrum and lattice parameter of silver particles against the cyclic exchange of ambient gases between 5% H2/He and 1% 02/He. The present data indicate that the adsorption of oxygen results in a reduction in surface stress of silver particles, leading to a change in the shape of particles.

In-situ High Temperature X-ray Diffraction Study of the Am-O System

MRS Advances ◽  
2016 ◽  
Vol 1 (62) ◽  
pp. 4133-4137 ◽  
Author(s):  
E. Epifano ◽  
R. C. Belin ◽  
J-C Richaud ◽  
R. Vauchy ◽  
M. Strach ◽  
...  
Keyword(s):  
High Temperature ◽  
Lattice Parameter ◽  
Minor Actinide ◽  
Controlled Atmosphere ◽  
X Ray Diffraction ◽  
X Ray ◽  
Binary Phase Diagrams ◽  
First Time ◽  
O Phase

ABSTRACTIn the frame of minor actinide recycling, (U,Am)O2 are promising transmutation targets. To assess the thermodynamic properties of the U-Am-O system, it is essential to have a thorough knowledge of the binary phase diagrams, which is difficult due to the lack of thermodynamic data on the Am-O system. Nevertheless, an Am-O phase diagram modelling has been recently proposed by Gotcu. Here, we show a recent investigation of the Am-O system using in-situ High Temperature X-ray Diffraction under controlled atmosphere. By coupling our experimental results with the thermodynamic calculations based on the Gotcu model, we propose for the first time a relation between the lattice parameter and the departure from stoichiometry.

RF-Magnetron Sputtered Strontium Titanate: Structure, Processing and Property Relationships

1999 ◽  
Vol 603 ◽  
Author(s):  
B.J. Gibbons ◽  
Y. Fan ◽  
A.T. Findikoglu ◽  
D.W. Reagor ◽  
Q.X. Jia
Keyword(s):  
Room Temperature ◽  
Low Frequency ◽  
Ozone Treatment ◽  
X Ray Diffraction ◽  
X Ray ◽  
Treated Sample ◽  
Diffraction Peaks ◽  
Compositional Variations ◽  
First Time

AbstractThe low frequency dielectric properties of epitaxial SrTiO3 thin films deposited on LaAlO3 are presented. The films were deposited using radio-frequency magnetron sputtering from stoichiometric targets in an Ar/O2 atmosphere. For the first time, the effects of in situ ozone annealing during the early stages of deposition were explored. X-ray diffraction results indicated that the ozone treatment resulted in more symmetric and sharper diffraction peaks (2 Θ- FWHM decreased from 0.17° to 0.10°). In addition, the peaks for the ozone treated samples were shifted in 2 Θ towards values approaching the bulk value. Rutherford backscattering measurements showed Sr/Ti ratios of 1:1 for these samples, indicating these peak shifts are not due to compositional variations. The dielectric constant of the ozone treated samples increased from 275 at room temperature to 1175 at 22 K (measured at 100 kHz). The effective loss tangent of the device remained between 1 × 10−4 and 1 × 10−3 down to 100 K, where it began to increase. The tunability was also measured. The ozone treated sample showed tunability of 46%, 43% and 38% at 22 K, 40 K and 60 K, respectively. Finally, similar measurements were completed at 1 MHz, indicating a minimal dependence of these properties on frequencies in this range.

Tracing the Alteration of Verdigris Pigment through Combined Raman Spectroscopy and X-ray Diffraction, Part II: Natural Ageing

2020 ◽  
Vol 41 (4) ◽  
pp. 177-203
Author(s):  
Lynn B. Brostoff ◽  
Cynthia Connelly Ryan ◽  
Isabella Black
Keyword(s):  
Raman Spectroscopy ◽  
Amorphous Material ◽  
Aqueous Media ◽  
Gum Arabic ◽  
Artificial Ageing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Paint Films ◽  
First Time

AbstractThis study explores the natural alteration of verdigris, both in the form of neutral verdigris (Cu(II) (CH3COO)2⋅H2O) and basic verdigris (Cu(II)x(CH3COO)y(OH)z ⋅nH2O), through combined Raman spectroscopy and X-ray diffraction investigation of samples created seven to eleven years prior to analysis. The naturally aged paint films of neutral or basic verdigris in gum arabic on paper and parchment provide insight into the pigment’s well-known instability relevant to historical works in aqueous media on maps, prints, books and manuscript materials. The latter historical application is an area that has received far less attention than alteration of verdigris in oil-based paint films. Findings shed new light on alternate pathways for conversion of neutral verdigris to basic verdigris, including the formation of a previously unknown form of verdigris and amorphous material on alkaline paper substrates. Additionally, we demonstrate for the first time that copper hydroxyl chlorides can form in situ from neutral verdigris, in this case on parchment that has a chlorine-rich surface. These results advance our understanding of neutral verdigris alteration, and complement results from our prior artificial ageing study. Both studies point to neutral verdigris as the historically more important form throughout its heyday. Improved understanding of neutral verdigris instability and its alteration pathways are critical for confident identification of the pigment in historical works, leading to better risk assessment of collections of verdigris-containing heritage, such as maps.

scholarly journals Ultrafast X-ray Diffraction Study of a Shock-Compressed Iron Meteorite above 100 GPa

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 567
Author(s):  
Sabrina Tecklenburg ◽  
Roberto Colina-Ruiz ◽  
Sovanndara Hok ◽  
Cynthia Bolme ◽  
Eric Galtier ◽  
...  
Keyword(s):  
Shock Compression ◽  
Iron Meteorite ◽  
Coarse Grained ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Hexagonal Close Packed ◽  
Natural Iron ◽  
First Time

Natural kamacite samples (Fe92.5Ni7.5) from a fragment of the Gibeon meteorite were studied as a proxy material for terrestrial cores to examine phase transition kinetics under shock compression for a range of different pressures up to 140 GPa. In situ time-resolved X-ray diffraction (XRD) data were collected of a body-centered cubic (bcc) kamacite section that transforms to the high-pressure hexagonal close-packed (hcp) phase with sub-nanosecond temporal resolution. The coarse-grained crystal of kamacite rapidly transformed to highly oriented crystallites of the hcp phase at maximum compression. The hcp phase persisted for as long as 9.5 ns following shock release. Comparing the c/a ratio with previous static and dynamic work on Fe and Fe-rich Fe-Ni alloys, it was found that some shots exhibit a larger than ideal c/a ratio, up to nearly 1.65. This work represents the first time-resolved laser shock compression structural study of a natural iron meteorite, relevant for understanding the dynamic material properties of metallic planetary bodies during impact events and Earth’s core elasticity.

High-temperature X-ray diffraction and thermal expansion of nanocrystalline and coarse-crystalline acanthite α-Ag2S and argentite β-Ag2S

2016 ◽  
Vol 18 (6) ◽  
pp. 4617-4626 ◽  
Author(s):  
S. I. Sadovnikov ◽  
A. I. Gusev ◽  
A. V. Chukin ◽  
A. A. Rempel
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Diffraction Method ◽  
Silver Sulfide ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Time

An in situ study of thermal expansion of polymorphic phases of coarse-crystalline and nanocrystalline silver sulfide – monoclinic acanthite α-Ag2S and cubic argentite β-Ag2S – has been carried out for the first time using the high-temperature X-ray diffraction method.

scholarly journals CO2 adsorption in Y zeolite: a structural and dynamic view by a novel principal-component-analysis-assisted in situ single-crystal X-ray diffraction experiment

2019 ◽  
Vol 75 (2) ◽  
pp. 214-222 ◽  
Author(s):  
Eleonora Conterosito ◽  
Luca Palin ◽  
Rocco Caliandro ◽  
Wouter van Beek ◽  
Dmitry Chernyshov ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Single Crystal ◽  
Principal Component ◽  
Active Species ◽  
Data Sets ◽  
X Ray Diffraction ◽  
Y Zeolite ◽  
X Ray ◽  
First Time

The increasing efficiency of detectors and brightness of X-rays in both laboratory and large-scale facilities allow the collection of full single-crystal X-ray data sets within minutes. The analysis of these `crystallographic big data' requires new tools and approaches. To answer these needs, the use of principal component analysis (PCA) is proposed to improve the efficiency and speed of the analysis. Potentialities and limitations of PCA were investigated using single-crystal X-ray diffraction (XRD) data collected in situ on Y zeolite, in which CO2, acting as an active species, is thermally adsorbed while cooling from 300 to 200 K. For the first time, thanks to the high sensitivity of single-crystal XRD, it was possible to determine the sites where CO2 is adsorbed, the increase in their occupancy while the temperature is decreased, and the correlated motion of active species, i.e. CO2, H2O and Na+. PCA allowed identification and elimination of problematic data sets, and better understanding of the trends of the occupancies of CO2, Na+ and water. The quality of the data allowed for the first time calculation of the enthalpy (ΔH) and entropy (ΔS) of the CO2 adsorption by applying the van 't Hoff equation to in situ single-crystal data. The calculation of thermodynamic values was carried out by both traditional and PCA-based approaches, producing comparable results. The obtained ΔH value is significant and involves systems (CO2 and Y zeolite) with no toxicity, superb stability and chemical inertness. Such features, coupled with the absence of carbonate formation and framework inertness upon adsorption, were demonstrated for the bulk crystal by the single-crystal experiment, and suggest that the phenomenon can be easily reversed for a large number of cycles, with CO2 released on demand. The main advantages of PCA-assisted analysis reside in its speed and in the possibility of it being applied directly to raw data, possibly as an `online' data-quality test during data collection, without any a priori knowledge of the crystal structure.

In Situ Deposition of CuBiS2 on Mesoporous TiO2 Film for Light Absorber in Solar Cells

2020 ◽  
Vol 20 (12) ◽  
pp. 7748-7752
Author(s):  
Peng-Cheng Wang ◽  
Feng-Zhu Li ◽  
Yu Zhang ◽  
Hao-Chen Fan ◽  
Xue-Qin Zhou ◽  
...  
Keyword(s):  
Energy Gap ◽  
Spectral Absorption ◽  
X Ray Diffraction ◽  
Solid Reaction ◽  
X Ray ◽  
In Situ Deposition ◽  
Light Absorber ◽  
Pure Phase ◽  
First Time

In this report, emplectite (CuBiS2) semiconductor has been deposited on mesoporous TiO2 using gas–solid reaction method. For the first time, CuCl2 and BiCl3 are solution-coated on mesoporous TiO2 films, and thereafter reacted with H2S gas in an H2S atmosphere. The CuBiS2 film is further confirmed using X-ray diffraction; thus, demonstrating the pure phase of CuBiS2. CuBiS2 film shows high spectral absorption with an energy gap (Eg) of 2.18 eV. Furthermore, devices have a structure consisting of FTO/compact-TiO2/mesoporous-TiO2/CuBiS2/P3HT/Ag have been fabricated and hence exhibit high photoresponse performance.

In situ high-temperature X-ray diffraction studies of reduction of K2CrO4 and the formation of KxCrOy compounds

2017 ◽  
Vol 32 (3) ◽  
pp. 168-174 ◽  
Author(s):  
Shu-ting Liang ◽  
Hong-ling Zhang ◽  
Min-ting Luo ◽  
Yu-lan Bai ◽  
Hong-bin Xu ◽  
...  
Keyword(s):  
Fourier Transform ◽  
High Temperature ◽  
Hydrogen Reduction ◽  
Potassium Chromate ◽  
Crystalline Material ◽  
Reduction Mechanism ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Time

In this work, the reduction mechanism of potassium chromate (K2CrO4) was investigated via in situ high-temperature X-ray diffraction coupled with Fourier transform infrared spectroscopy. During the hydrogen reduction of K2CrO4, the formation of K3CrO4, KCrO2, and KxCrO2 were detected for the first time. The study discovered that K2CrO4 was firstly reduced to K3CrO4 and an amorphous Cr(III) intermediate product at low temperature (400–500 °C). Moreover, the K3CrO4 was the only crystalline material at this stage. As the temperature increased, a stabilized amorphous CrOOH was formed. At a high temperature (550–700 °C), KCrO2 was generated. Interestingly, a portion of KCrO2 was spontaneously decomposed during the hydrogen reduction, accompanying by the formation of K0.7CrO2. Finally, the results clearly illustrated the reduction mechanism of K2CrO4: K2CrO4 → K3CrO4 → amorphous intermediate → KCrO2.

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