scholarly journals IDM-1, a New Zeolite with Intersecting Medium and Extra-Large Pores Built as an Expansion of Zeolite MFI

2020 ◽  
Author(s):  
Luis Angel Villaescusa ◽  
Jian Li ◽  
Zihao Gao ◽  
Junliang Sun ◽  
Miguel Camblor
Keyword(s):  
Thermal Stability ◽  
Electron Diffraction ◽  
Diffraction Data ◽  
Catalytic Properties ◽  
High Thermal Stability ◽  
X Ray Diffraction ◽  
X Ray ◽  
Unique Structure ◽  
Chemical Character

<p> IDM-1 is a new silica zeolite with an ordered and well-defined framework constructed by alternating pentasil layers and interrupted layers, giving rise to an intersecting system of straight medium pores and undulating extra-large lobed pores. This unique structure was solved by rotation electron diffraction and refined against synchrotron powder X-ray diffraction data. Despite the presence of both Si(OSi)<sub>3</sub>(OH) and Si(OSi)<sub>2</sub>(OH)<sub>2</sub> sites, this new zeolite presents high thermal stability, withstanding calcination even to 1000ºC. The location of defects at specific sites of the structure results in alternating hydrophobic SiO<sub>2</sub> and hydrophilic SiO<sub>(2-x)</sub>(OH)<sub>2x</sub> intracrystalline regions. This peculiar combination of intersecting medium and extra-large pores and alternating regions of different chemical character may provide this zeolite with unique catalytic properties.</p>

scholarly journals IDM-1, a New Zeolite with Intersecting Medium and Extra-Large Pores Built as an Expansion of Zeolite MFI

2020 ◽  
Author(s):  
Luis Angel Villaescusa ◽  
Jian Li ◽  
Zihao Gao ◽  
Junliang Sun ◽  
Miguel Camblor
Keyword(s):  
Thermal Stability ◽  
Electron Diffraction ◽  
Diffraction Data ◽  
Catalytic Properties ◽  
High Thermal Stability ◽  
X Ray Diffraction ◽  
X Ray ◽  
Unique Structure ◽  
Chemical Character

<p> IDM-1 is a new silica zeolite with an ordered and well-defined framework constructed by alternating pentasil layers and interrupted layers, giving rise to an intersecting system of straight medium pores and undulating extra-large lobed pores. This unique structure was solved by rotation electron diffraction and refined against synchrotron powder X-ray diffraction data. Despite the presence of both Si(OSi)<sub>3</sub>(OH) and Si(OSi)<sub>2</sub>(OH)<sub>2</sub> sites, this new zeolite presents high thermal stability, withstanding calcination even to 1000ºC. The location of defects at specific sites of the structure results in alternating hydrophobic SiO<sub>2</sub> and hydrophilic SiO<sub>(2-x)</sub>(OH)<sub>2x</sub> intracrystalline regions. This peculiar combination of intersecting medium and extra-large pores and alternating regions of different chemical character may provide this zeolite with unique catalytic properties.</p>

Preparation of Anion Modified Montmorillonite-Polystyrene Nanocomposite by Suspension Polymerization

2009 ◽  
Vol 87-88 ◽  
pp. 499-503
Author(s):  
Yi Wang ◽  
Hui Xia Feng ◽  
Jian Hui Qiu
Keyword(s):  
Thermal Stability ◽  
Anionic Surfactants ◽  
Suspension Polymerization ◽  
Layered Silicate ◽  
High Thermal Stability ◽  
X Ray Diffraction ◽  
X Ray ◽  
Modified Montmorillonite ◽  
Silicate Nanocomposites ◽  
Ft Ir

To ensure good compatibility between polymer and montmorillonite (MMT), three types organophilic-MMT were prepared and the influence of modifying agent style on the modification effect was studied. The results of X-ray diffraction(XRD) show that the modified reagents are all intercalated into the galleries of MMT, which are also proved by patterns of FT-IR and thermogravimetric analysis(TGA), and the spacing of MMT layers increases from 1.23 nm of the pristine MMT to 2.10nm, 3.52nm and 4.14nm for CTAB, SDS and DBS modified MMT respectively. The results also indicate that the d-spacing and exfoliation degree of anionic surfactants inserted MMT is bigger than that of the cationic surfactants treated MMT, which are usually used to preparation polymer layered silicate nanocomposites in literatures. So PS/SDS-MMT and PS/DBS-MMT nanocomposites were prepared by suspension polymerization. The structure of complex were characterized by XRD and no peak can be observed by the spectra, which suggest that the clay platelets have been exfoliated and dispersed in the PS matrix and the both complex are all have exfoliated structure. FT-IR spectrums analysis confirmed the existence of MMT which implied that the layers of silicate was distributing in composites. The results of TGA show that nanocomposites possess exceptionally high thermal stability and the DBS treated composite has higher thermal stability than that of SDS treated.

A complex pseudo-decagonal quasicrystal approximant, Al37(Co,Ni)15.5, solved by rotation electron diffraction

2014 ◽  
Vol 47 (1) ◽  
pp. 215-221 ◽  
Author(s):  
Devinder Singh ◽  
Yifeng Yun ◽  
Wei Wan ◽  
Benjamin Grushko ◽  
Xiaodong Zou ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Single Crystal ◽  
Diffraction Data ◽  
Three Dimensional ◽  
Basic Structure ◽  
Electron Diffraction Data ◽  
Dimensional Electron ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns

Electron diffraction is a complementary technique to single-crystal X-ray diffraction and powder X-ray diffraction for structure solution of unknown crystals. Crystals too small to be studied by single-crystal X-ray diffraction or too complex to be solved by powder X-ray diffraction can be studied by electron diffraction. The main drawbacks of electron diffraction have been the difficulties in collecting complete three-dimensional electron diffraction data by conventional electron diffraction methods and the very time-consuming data collection. In addition, the intensities of electron diffraction suffer from dynamical scattering. Recently, a new electron diffraction method, rotation electron diffraction (RED), was developed, which can overcome the drawbacks and reduce dynamical effects. A complete three-dimensional electron diffraction data set can be collected from a sub-micrometre-sized single crystal in less than 2 h. Here the RED method is applied forab initiostructure determination of an unknown complex intermetallic phase, the pseudo-decagonal (PD) quasicrystal approximant Al37.0(Co,Ni)15.5, denoted as PD2. RED shows that the crystal is F-centered, witha= 46.4,b= 64.6,c= 8.2 Å. However, as with other approximants in the PD series, the reflections with oddlindices are much weaker than those withleven, so it was decided to first solve the PD2 structure in the smaller, primitive unit cell. The basic structure of PD2 with unit-cell parametersa= 23.2,b= 32.3,c= 4.1 Å and space groupPnmmhas been solved in the present study. The structure withc= 8.2 Å will be taken up in the near future. The basic structure contains 55 unique atoms (17 Co/Ni and 38 Al) and is one of the most complex structures solved by electron diffraction. PD2 is built of characteristic 2 nm wheel clusters with fivefold rotational symmetry, which agrees with results from high-resolution electron microscopy images. Simulated electron diffraction patterns for the structure model are in good agreement with the experimental electron diffraction patterns obtained by RED.

On the quality of the continuous rotation electron diffraction data for accurate atomic structure determination of inorganic compounds

2018 ◽  
Vol 51 (4) ◽  
pp. 1094-1101 ◽  
Author(s):  
Yunchen Wang ◽  
Taimin Yang ◽  
Hongyi Xu ◽  
Xiaodong Zou ◽  
Wei Wan
Keyword(s):  
Electron Diffraction ◽  
Single Crystal ◽  
Diffraction Data ◽  
Structural Models ◽  
Electron Diffraction Data ◽  
Data Sets ◽  
X Ray Diffraction ◽  
X Ray ◽  
Continuous Rotation

The continuous rotation electron diffraction (cRED) method has the capability of providing fast three-dimensional electron diffraction data collection on existing and future transmission electron microscopes; unknown structures could be potentially solved and refined using cRED data collected from nano- and submicrometre-sized crystals. However, structure refinements of cRED data using SHELXL often lead to relatively high R1 values when compared with those refined against single-crystal X-ray diffraction data. It is therefore necessary to analyse the quality of the structural models refined against cRED data. In this work, multiple cRED data sets collected from different crystals of an oxofluoride (FeSeO3F) and a zeolite (ZSM-5) with known structures are used to assess the data consistency and quality and, more importantly, the accuracy of the structural models refined against these data sets. An evaluation of the precision and consistency of the cRED data by examination of the statistics obtained from the data processing software DIALS is presented. It is shown that, despite the high R1 values caused by dynamical scattering and other factors, the refined atomic positions obtained from the cRED data collected for different crystals are consistent with those of the reference models refined against single-crystal X-ray diffraction data. The results serve as a reference for the quality of the cRED data and the achievable accuracy of the structural parameters.

A New Synthetic Route to Calcium Polyphosphates

2005 ◽  
Vol 284-286 ◽  
pp. 71-74 ◽  
Author(s):  
Lauren E. Jackson ◽  
Adrian J. Wright
Keyword(s):  
Thermal Stability ◽  
Diffraction Data ◽  
Crystalline Phase ◽  
Single Step ◽  
Synthetic Route ◽  
X Ray Diffraction ◽  
Subsequent Increase ◽  
X Ray ◽  
Calcium Polyphosphate ◽  
Thermal Stability Of

This study describes the use of flux methods as a novel synthetic route to some known and new calcium polyphosphates, with a view to developing new biomaterials. Calcium acid pyrophosphate, CaH2P2O7, which is a known precursor in the preparation of many other calcium polyphosphates, has been synthesized as a pure crystalline phase in a single step synthesis at temperatures between 190-250 °C. Reaction temperatures between 250 and 400 °C led to the synthesis of γ-Ca(PO3)2, a previously uncharacterised polymorph of calcium metaphosphate. Lattice parameters of a = 10.3682(1) Å, b = 9.5001(1) Å, c = 9.5552(1) Å, with β angle of 93.45(4)° were obtained from powder X-ray diffraction data. A subsequent increase in reaction temperature to 550 °C was found to produce a calcium polyphosphate glass. A detailed study of thermal stability of CaH2P2O7 was also performed to determine phase stability and decomposition pathways.

The EISI Index: A Search/ Match Tool for Electron Diffraction Phase Analysis

1990 ◽  
Vol 48 (2) ◽  
pp. 514-515
Author(s):  
Ron Anderson ◽  
M. J. Carr ◽  
V. L. Himes ◽  
A. D. Mighell
Keyword(s):  
Electron Diffraction ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
Diffraction Intensity ◽  
Chemical Thermodynamic ◽  
Powder Diffraction File ◽  
X Ray ◽  
Unknown Phase ◽  
Intensity Information

The identification of unknown phases using diffraction data and the JCPDS-ICDD Powder Diffraction File (PDF)[1] is a three-step process. First, the Search step rapidly screens the entire PDF to produce a list of candidate solutions that correspond to the unknown phase’s d-spacings and chemistry. Second, the Match step examines closely every aspect of each phase in the candidate list, vs. the unknown, to make the identification. Third, the Decision step: does the solution found make crystal-chemical-thermodynamic sense? A hindrance to the identification process for electron diffraction applications is that the PDF consists of X-ray powder diffraction data. There are two problems: First, while X-ray diffraction intensity data compares well to electron diffraction intensities for randomly-oriented, small-grained specimens, in the main, intensities from the two methods are not the same. The differing intensities exacerbate the problem of unknown phase searching for electron diffraction because X-ray derived Search/Matching methods rely heavily on intensity information.

X-ray powder diffraction data for Al73.5Ni18.5Re8 orthorhombic phase

2008 ◽  
Vol 23 (3) ◽  
pp. 251-254 ◽  
Author(s):  
B. Grushko ◽  
S. Balanetskyy
Keyword(s):  
Electron Diffraction ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Ternary Phase ◽  
Orthorhombic Phase ◽  
Powder Diffraction Data ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compositional Range

A ternary phase was revealed in Al-Ni-Re in a small compositional range around Al73.5Ni18.5Re8. Using powder X-ray diffraction and electron diffraction, it was found to have an orthorhombic structure with a=10.048(3) Å, b=15.423(8) Å, and c=8.367(3) Å.

The Molecular Structure and Hydrogen Bond Geometry in Liquid Formamide: Electron, Neutron, and X-Ray Diffraction Studies

1983 ◽  
Vol 38 (2) ◽  
pp. 231-236 ◽  
Author(s):  
E. Kálmán ◽  
I. Serke ◽  
G. Pálinkás ◽  
M. D. Zeidler ◽  
F. J. Wiesmann ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Hydrogen Bond ◽  
Electron Diffraction ◽  
Diffraction Data ◽  
Free Molecule ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Mean ◽  
Diffraction Patterns ◽  
Good Agreement

Abstract Electron, neutron and X-ray diffraction patterns of liquid formamide have been measured at a temperature of 25 °C. Analysis of the diffraction data yields the molecular structure and the average geometry of the hydrogen bond. The molecular parameters obtained from liquid diffraction experiments are in good agreement with those from gas electron diffraction for the free molecule. The mean O…N and O…H hydrogen bond distances are 2.9 Å and 1.9 Å, respectively. Four H-bonds per molecule are found on the average. The deviation of the H-bonds from the linearity is estimated.

Thermally Stable 3,6-Disubstituted 1,2,4,5-Tetrazines

2013 ◽  
Vol 68 (12) ◽  
pp. 1310-1320 ◽  
Author(s):  
Thomas M. Klapötke ◽  
Andreas Preimesser ◽  
Jörg Stierstorfer
Keyword(s):  
Mass Spectrometry ◽  
Thermal Stability ◽  
High Thermal Stability ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
H Nmr ◽  
New Compounds ◽  
Very High ◽  
C Nmr

Several 3,6-disubstituted 1,2,4,5-tetrazines were synthesized by nucleophilic substitution using 3,6-bis-(3,5-dimethyl-pyrazol-1-yl)-1,2,4,5-tetrazine and 3,6-dichloro-1,2,4,5-tetrazine as electrophiles. All new compounds were characterized by 1H NMR, 13C NMR and vibrational spectroscopy, mass spectrometry and elemental analysis (C,H,N). For analysis of the thermostability, differential scanning calorimetry (DSC) was used. Especially, the symmetrically bis-3,5-diamino-1,2,4- triazolyl-substituted derivative shows a very high thermal stability up to 370 °C. Therefore its energetic properties were determined and compared with thoses of hexanitrostilbene (HNS). The crystal structures of 3,6-bishydrazino-1,2,4,5-tetrazine, 3,6-dichloro-1,2,4,5-tetrazine and 3-amino-6-(3,5- diamino-1,2,4-triazol-1-yl)-1,2,4,5-tetrazine dihydrate have been determined by low-temperature X-ray diffraction

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