Relationship Between Crystal Structure, Internal Stress and Properties in the Naturally Occurring Supportless Thin Films of Chrysotile Asbestos

1994 ◽  
Vol 356 ◽  
Author(s):  
Georges Denes ◽  
R. Le Van Mao ◽  
A. Vaillancourt
Keyword(s):  
Direct Consequence ◽  
Structural Formula ◽  
Thin Layers ◽  
Magnesium Ions ◽  
Chrysotile Asbestos ◽  
X Ray Diffraction ◽  
X Ray ◽  
Naturally Occurring ◽  
Enormous Amount ◽  
Unit Cells

AbstractChrysotile asbestos (empirical formula: Mg3Si2O7.2H2O, structural formula: Mg3Si2O5(OH)4) crystallizes in a sheet structure so thin that it is equivalent to a thin film that has no support. The magnesium ions are too large to fit comfortably in their octahedral sites, the size of which is determined by the network of SiO4 tetrahedra. The squeezing of the magnesium ions in sites that are too tight forces the thin layers to bend and coil around themselves. The bending of the unit-cells results in the presence of an enormous amount of highly directional stress, which has been analyzed by X-ray diffraction. The carcinogenic properties of chrysotile asbestos are a direct consequence of this stress.

High Resolution Replication of Organoclay Surfaces

1982 ◽  
Vol 40 ◽  
pp. 576-577
Author(s):  
W. W. Barker ◽  
W. E. Rigsby ◽  
V. J. Hurst ◽  
W. J. Humphreys
Keyword(s):  
Clay Mineral ◽  
Organic Molecule ◽  
Organic Molecules ◽  
X Ray Diffraction ◽  
Xrd Pattern ◽  
X Ray ◽  
Naturally Occurring ◽  
Silicate Layers ◽  
Mineral Identification

Experimental clay mineral-organic molecule complexes long have been known and some of them have been extensively studied by X-ray diffraction methods. The organic molecules are adsorbed onto the surfaces of the clay minerals, or intercalated between the silicate layers. Natural organo-clays also are widely recognized but generally have not been well characterized. Widely used techniques for clay mineral identification involve treatment of the sample with H2 O2 or other oxidant to destroy any associated organics. This generally simplifies and intensifies the XRD pattern of the clay residue, but helps little with the characterization of the original organoclay. Adequate techniques for the direct observation of synthetic and naturally occurring organoclays are yet to be developed.

scholarly journals Hydrochloric Acid Modification and Lead Removal Studies on Naturally Occurring Zeolites from Nevada, New Mexico, and Arizona

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1238
Author(s):  
Garven M. Huntley ◽  
Rudy L. Luck ◽  
Michael E. Mullins ◽  
Nick K. Newberry
Keyword(s):  
New Mexico ◽  
Surface Area ◽  
Bet Surface Area ◽  
Lead Removal ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Naturally Occurring ◽  
27Al Mas Nmr ◽  
Modified Zeolites

Four naturally occurring zeolites were examined to verify their assignments as chabazites AZLB-Ca and AZLB-Na (Bowie, Arizona) and clinoptilolites NM-Ca (Winston, New Mexico) and NV-Na (Ash Meadows, Nevada). Based on powder X-ray diffraction, NM-Ca was discovered to be mostly quartz with some clinoptilolite residues. Treatment with concentrated HCl (12.1 M) acid resulted in AZLB-Ca and AZLB-Na, the chabazite-like species, becoming amorphous, as confirmed by powder X-ray diffraction. In contrast, NM-Ca and NV-Na, which are clinoptilolite-like species, withstood boiling in concentrated HCl acid. This treatment removes calcium, magnesium, sodium, potassium, aluminum, and iron atoms or ions from the framework while leaving the silicon framework intact as confirmed via X-ray fluorescence and diffraction. SEM images on calcined and HCl treated NV-Na were obtained. BET surface area analysis confirmed an increase in surface area for the two zeolites after treatment, NM-Ca 20.0(1) to 111(4) m2/g and NV-Na 19.0(4) to 158(7) m2/g. 29Si and 27Al MAS NMR were performed on the natural and treated NV-Na zeolite, and the data for the natural NV-Na zeolite suggested a Si:Al ratio of 4.33 similar to that determined by X-Ray fluorescence of 4.55. Removal of lead ions from solution decreased from the native NM-Ca, 0.27(14), NV-Na, 1.50(17) meq/g compared to the modified zeolites, 30 min HCl treated NM-Ca 0.06(9) and NV-Na, 0.41(23) meq/g, and also decreased upon K+ ion pretreatment in the HCl modified zeolites.

Structural Study of an Unusual Diels-Alder Adduct

1992 ◽  
Vol 45 (12) ◽  
pp. 2089 ◽  
Author(s):  
EL Ghisalberti ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Diffraction Study ◽  
Structural Study ◽  
Spectroscopic Studies ◽  
Diels Alder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Naturally Occurring ◽  
Chemical Evidence ◽  
Alder Adduct

The structure of the compound obtained on heating the naturally occurring clerodane furanoditerpene (1) had been formulated as (2) on the basis of spectroscopic studies. A single-crystal X-ray diffraction study on the dihydro derivative of (2) has confirmed this and provides support for the stereochemistry previously assigned to (1) on the basis of chemical evidence.

STRUCTURAL AND ELECTROCHEMICAL PROPERTIES OF THIN LAYERS OF BINARY Ni–Fe ALLOYS ELECTRODEPOSITED BY TWO DIFFERENT BATHS: ACID AND IONIC LIQUID

2018 ◽  
Vol 25 (08) ◽  
pp. 1950025
Author(s):  
RAFIK MAIZI ◽  
ATHMANE MEDDOUR ◽  
CÉLINE ROUSSE
Keyword(s):  
Ionic Liquid ◽  
Nickel Content ◽  
Deposition Potential ◽  
Thin Layers ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Different Shapes ◽  
Fe Alloys ◽  
Irregular Behavior

The deposition of Ni–Fe thin layers in boric acid and ionic liquid ([BuMePyr][Tf2N]) baths were successfully prepared. The obtained materials have been characterized by X-ray diffraction (XRD), Energy Dispersive X-ray spectroscopy (EDX) and SEM. Meanwhile, these materials were carried out by chronoamperometry or chronopotentiometry by varying the intensity of the current and the deposition potential. The results indicate that the coatings of Ni–Fe alloys were successfully obtained by electroplating on the copper substrates, and the alloys composition shows irregular behavior with polarization. The nickel content in the samples is in the range of 55–90%, but the iron content ranges from 10–30%, when potential deposits were varied from [Formula: see text]2[Formula: see text]V to [Formula: see text]4[Formula: see text]V vs Ni electrode. The results also showed that the thin layers are monophased; they contain the Ni3Fe phase. Further, SEM images of Ni–Fe alloys show the different shapes of particles.

scholarly journals Synergistic interaction of renewable nipagin and eugenol for high performance aromatic copoly(ether ester) materials

2021 ◽  
Author(s):  
Keling Hu ◽  
Huachao Sui ◽  
Dongping Zhao
Keyword(s):  
High Performance ◽  
Synergistic Interaction ◽  
Differential Scanning Calorimetric ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molecular Weights ◽  
Chemical Structures ◽  
Naturally Occurring ◽  
Ether Ester

Abstract Naturally occurring nipagin and eugenol were used as the collaborative starting materials for poly(ether ester) materials. In this study, two series of nipagin and eugenol-derived copoly(ether ester)s, PHN11-xE1x and PHN11-xE2x (x = 0%, 5%, 10%, 15%, 20%), were prepared with renewable 1,6-hexanediol as a comonomer. The nipagin-derived component acts as the renewable surrogate of petroleum-based dimethyl terephthalate (DMT), while the eugenol-derived component acts as the cooperative property modifier of parent homopoly(ether ester) PHN1. 1,6-Hexanediol was chosen as the spacer because of its renewability and short chain to enhance the glass transition temperatures (Tgs) of materials. The molecular weights and chemical structures were confirmed by gel permeation chromatograph (GPC), NMR and FTIR spectroscopies. Thermal and crystalline properties were studied by thermal gravimetric analysis (TGA), differential scanning calorimetric (DSC) and wide-angle X-ray diffraction (WXRD). The tensile assays were conducted to evaluate the mechanical properties. The results suggest that properties of such kind of poly(ether ester)s can be finely tuned by the relative content of two components. Synergistic interaction of two structurally distinctive parts endows the materials with high performance.

scholarly journals Microbialite-like structures in Cladophora sp. (Ulvophyceae) mats from a subtropical Andean basin: ecological implications

2019 ◽  
Vol 67 (1) ◽  
Author(s):  
Hugo R. Fernández ◽  
Ana Lucia Gonzalez Achem ◽  
Marcela Correa ◽  
Virginia H. Albarracín
Keyword(s):  
Organic Pollution ◽  
Biological Factors ◽  
X Ray Diffraction ◽  
Calcite Precipitation ◽  
Annual Cycles ◽  
X Ray ◽  
Naturally Occurring ◽  
Ecological Implications ◽  
First Time ◽  
Solubility Equilibrium

The solubility equilibrium of calcite is influenced by physicochemical, climatic and biological factors. Annual cycles of exceptionally prolonged drought, in conjunction with naturally occurring diffuse organic pollution, generate the unique conditions for the precipitation of lithified carbonate structures (microbialites). The aim of this article is to analyze the possible implications of calcite precipitation produced in mats of Cladophora sp. in an Andean subtropical basin, considering it is the first time this phenomenon is described for the region. We collected samples from selected sites at the Lules River Basin, in four sampling dates between the years 2003 and 2004, within a monitoring work of 15 years. Samples were analyzed using an electron microscope and X-ray diffraction analysis. We found that Gomphonema sp. attached to Cladophora sp. contributes to precipitation of calcite and formation of microbialite like structures, in the studied area. This work presents an initial discussion of the discovery of microbialites-like structures attached to Cladophora sp. mats in a subtropical Andean stream and the environmental conditions that lead to their production, as well as the possible ecological implications of these microbialites.

Study on the phase structure and mechanical properties of (Ti,Al,Si)N coatings deposited by multiarc ion plating

2019 ◽  
Vol 34 (01n03) ◽  
pp. 2040043
Author(s):  
Mengchao Wang ◽  
Lijun Wang ◽  
Hui Chen ◽  
Yinfen Cheng
Keyword(s):  
Cross Sections ◽  
Phase Structure ◽  
Structural Formula ◽  
Columnar Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ion Plating ◽  
Substrate Adhesion ◽  
Scratch Tests ◽  
Angular Shift

Different structural [Formula: see text] coatings were designed and deposited on WC-Co cemented carbide by the technology of multiarc ion plating. Monolayered [Formula: see text] coating was deposited using cathode of [Formula: see text]. Multilayered (Ti,Al)N/[Formula: see text] coating and [Formula: see text] coating with gradual silicon content were deposited using two cathodes of [Formula: see text] and [Formula: see text] simultaneously. The surface and cross-section morphology, compositions, and phase structure were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The dense [Formula: see text] coatings with droplets on the surface and without obvious columnar structure on the cross-sections were obtained. All coatings had the strong peaks of (200) orientation. The different angular shift occurred with different combination of cathodes and processes. The introduction of multilayered and gradient structure effectively reduced the lattice distortion of coatings. Meanwhile, the coating-substrate adhesion strength increased from 38.57 N to 60.17 N with a coating thickness of approximately 3.5 [Formula: see text]m by scratch tests. The highest hardness of [Formula: see text] coating obtained in this paper were [Formula: see text] GPa by nanoindentation. The multilayered coating showed better toughness.

Hierarchical structure of the triclinic α-phase crystal in nylon 6,12 mediated by two-dimensional confinement

2020 ◽  
Vol 53 (1) ◽  
pp. 27-33
Author(s):  
Ziwei Lai ◽  
Shuailin Zhang ◽  
Nan Zheng ◽  
Shichen Yu ◽  
Masaki Ageishi ◽  
...  
Keyword(s):  
Hierarchical Structure ◽  
Phase Cell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hierarchical Nanostructure ◽  
Α Phase ◽  
Triclinic Symmetry ◽  
Phase Crystal ◽  
Unit Cells ◽  
The Impact

It has been recognized that macromolecular chains can self-assemble into a hierarchical structure from lamellae to spherulites in bulk crystallization. However, little account has been taken of crystal symmetry effects on the hierarchical nanostructure in polymers under cylindrical confinement. In this research, a model polymer, nylon 6,12, most commonly occurring in the triclinic α phase, was chosen in order to demonstrate the effect of triclinic symmetry on the 2D-constrained polymer nanostructure. The self-arranging unit of nylon 6,12 takes various forms, including stems, unit cells, hydrogen-bonded sheets, lamellae and complex spherulites, which is an essential structural feature for investigating hierarchical nanostructure. The rod nanostructure in confinement was examined by cross-checking electron and X-ray diffraction techniques. It is found that the a* axis of the α-phase cell is inclined at about ±6–11° to the rod long axis within the a*b* plane around the c axis (c axis ⊥ rod long axis). The rotation of the a*b* plane most likely results from the impact of the triclinic symmetry on the molecular chain packing under 2D confinement. A mechanism for this a*b* plane tilting is proposed.

Powder X-Ray Diffraction Data for the Superconducting Phase TlCaBa2Cu2O7−δ

1992 ◽  
Vol 7 (2) ◽  
pp. 115-116 ◽  
Author(s):  
Terry L. Aselage ◽  
Michael O. Eatough
Keyword(s):  
Cuprate Superconductors ◽  
General Interest ◽  
Superconducting Transition ◽  
X Ray Diffraction ◽  
Pure Compound ◽  
Group 14 ◽  
X Ray ◽  
Superconducting Phases ◽  
The Family ◽  
Unit Cells

High temperature superconducting phases in the Tl-Ca-Ba-Cu-O system are ideally represented by the formula TlmCan−1Ba2CunO2(n+1)+m, with m either 1 or 2 and n = 1 to at least 3 (Parkin et at., 1988). Each of these phases contains one or more of the nearly planar CuO2sheets common to the cuprate superconductors. A single Ca atom separates adjacent CuO2sheets (n > 1). Single or double rock salt-like Tl-O layers are separated from the Can−1CunO2nregions by single Ba-O layers. Each of the Ca-containing members of this family crystallizes in a tetgragonal unit cell, with space group 14/mmm for the m = 2 series and P4/mmm for the m = 1 series.Despite the general interest in this family of superconductors, little has been reported about the m = 1, n = 2 member, TlCaBa2Cu2O7−δ, hereafter called 1122. This lack of work is due at least in part to the difficulty in synthesizing the pure compound (Michel et at., 1991). Additionally, technological interest has focused on members of the family with higher superconducting transition temperatures, particularly Tl2Ca2Ba2Cu3Oywith Tcup to 125 K. The critical temperature of 1122 has been reported from as low as 50 K (Hervieu et al., 1988) to as high as 103 K (Morosin et al., 1988), and at several values in between (Ganguli et al., 1988; Liang et al., 1988). Most of the samples had other superconducting phases in addition to 1122. Because of the nearly identical a axis lengths of the unit cells of the Tl-family of superconductors, syntactic intergrowths may be present in such multiphase samples.

ENHANCEMENT OF ENERGY PRODUCT WITH INSERTION OF Ti BETWEEN EXCHANGE COUPLED Sm–Co AND Fe LAYERS

2011 ◽  
Vol 25 (22) ◽  
pp. 2957-2963 ◽  
Author(s):  
FURRUKH SHAHZAD ◽  
SAADAT ANWAR SIDDIQI ◽  
SHI-SHEN YAN ◽  
M. SABIEH ANWAR ◽  
S. M. RAMAY
Keyword(s):  
Elevated Temperature ◽  
Exchange Coupling ◽  
Single Phase ◽  
Rf Magnetron Sputtering ◽  
Thin Layers ◽  
Interlayer Thickness ◽  
X Ray Diffraction ◽  
X Ray ◽  
Energy Product ◽  
Strong Exchange

Bilayers of Sm – Co / Fe have been fabricated on 70 nm Cr buffered Si (100) substrate at an elevated temperature of 650°C by the help of DC and RF magnetron sputtering. Very thin layers (0–0.7 nm) of Ti were introduced at the interface of the Sm – Co and Fe phases. The samples were analyzed by X-ray diffraction (XRD) and alternating gradient magnetometer (AGM). All the samples showed strong exchange coupling and single phase behavior. The rise and fall in magnetization and energy product were observed with increasing Ti interlayer thickness. Energy product (BH) max value was found increased by 44% for 0.2 nm Ti interlayer as compared to the sample without Ti layer at interface.

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