Corrensite and chlorite-rich Chl-S mixed layers in sandstones from the ‘Macigno’ Formation (northwestern Tuscany, Italy)

Clay Minerals ◽  
2010 ◽  
Vol 45 (1) ◽  
pp. 87-106 ◽  
Author(s):  
L. Leoni ◽  
M. Lezzerini ◽  
S. Battaglia ◽  
F. Cavalcante
Keyword(s):  
Long Range ◽  
Coefficient Of Variation ◽  
Basal Spacing ◽  
Stacking Sequence ◽  
X Ray ◽  
Transition Boundary ◽  
Long Range Ordering ◽  
Mixed Layers ◽  
Ray Patterns

AbstractCorrensite and chlorite-rich chlorite-smectite (Chl-S) mixed-layers occurring in the Macigno Formation of northwestern Tuscany were investigated by XRPD/SEM techniques. The samples from the Macigno outcrops were affected by metamorphism corresponding to the high-diagenesis/low-anchizone transition boundary. The basal spacing of corrensite measured from 00l reflections on EG–Mg2+-saturated samples ranges from 30.97 to 31.18 Å with a coefficient of variation (CV) of 0.46–0.77%, consistent with the rational pattern of a 1:1 Chl-S periodic stacking sequence. X-ray patterns of heated K+-saturated specimens reveal the presence of two types of corrensite, probably with different interlayer charges on their respective smectite-like layers. The chlorite-rich Chl-S mixed layers coexisting with corrensite consist of R2 chlorite (0.70–0.75)/S and chlorite (0.90)/S with long-range ordering R ⩾ 1. SEM observations show that corrensite and chlorite-rich Chl-S mixed-layers are closely mixed on a sub-micron scale. Some grains of corrensite and chlorite-rich Chl-S mixed-layers include zones (2–10 μm) of chlorite composition, as shown by microprobe analyses.

Relationship between low-Q peak and long-range ordering of ionic liquids revealed by high-energy X-ray total scattering

2015 ◽  
Vol 17 (27) ◽  
pp. 17838-17843 ◽  
Author(s):  
Kenta Fujii ◽  
Shinji Kohara ◽  
Yasuhiro Umebayashi
Keyword(s):  
Ionic Liquids ◽  
Long Range ◽  
High Energy ◽  
Real Space ◽  
Space Structure ◽  
Total Scattering ◽  
X Ray ◽  
Peak Intensity ◽  
Long Range Ordering

A new function, SQpeak(r); a connection between low-Q peak intensity with real space structure.

Coexistence of 1 : 2 and 1 : 1 long-range ordering types in La-modified Ba(Mg0.33Ta0.67)O3 ceramics

1997 ◽  
Vol 12 (3) ◽  
pp. 589-592 ◽  
Author(s):  
Hyuk-Joon Youn ◽  
Kug Sun Hong ◽  
Hwan Kim
Keyword(s):  
Solid Solution ◽  
Dielectric Properties ◽  
Long Range ◽  
Phase Coexistence ◽  
Microwave Measurements ◽  
X Ray Diffraction ◽  
Physical Origin ◽  
X Ray ◽  
Wide Range ◽  
Long Range Ordering

The ordering structure of lanthanum-substituted Ba(Mg0.33Ta0.67)O3 was investigated using x-ray diffraction. It was observed that the ordering type of this solid solution transformed from 1: 2 to 1: 1 with 10 mol% substitution of La(Mg0.67Ta0.33)O3. These two types of ordering coexist over a wide range of composition. This coexistence of ordering types was considered as phase coexistence and its physical origin was investigated using microwave measurements. Based on the intensity of superlattice reflections and the discontinuity in dielectric properties, it was suggested that the coexistence of two ordering types originates from the overlap of the two stability regions.

Determination of average carbon number of petroleum waxes by X-ray diffraction

2008 ◽  
Vol 41 (5) ◽  
pp. 950-951 ◽  
Author(s):  
Sanat Kumar ◽  
S. P. Srivastava ◽  
H. U. Khan
Keyword(s):  
Melting Point ◽  
Long Range ◽  
Carbon Number ◽  
High Melting ◽  
X Ray Diffraction ◽  
High Melting Point ◽  
X Ray ◽  
Long Range Ordering ◽  
Standard Gas

Eight petroleum waxes, both paraffin as well as microcrystalline, have been analysed by X-ray diffraction. The average carbon number has been estimated by the long-range ordering observed in the diffractograms of these waxes. The average carbon number has also been determined following the standard gas chromatographic (GC) method. The results obtained by X-ray diffractometry compare well with those obtained by the GC method. The former method also permits determination of the average carbon number of high melting point waxes, which is otherwise difficult using GC.

Wrinkled-up Nanochannel Networks: Long-Range Ordering, Scalability, and X-ray Investigation

ACS Nano ◽  
2008 ◽  
Vol 2 (8) ◽  
pp. 1715-1721 ◽  
Author(s):  
Angelo Malachias ◽  
Yongfeng Mei ◽  
Ratna K. Annabattula ◽  
Christoph Deneke ◽  
Patrick R. Onck ◽  
...  
Keyword(s):  
Long Range ◽  
X Ray ◽  
Long Range Ordering

Opal, cristobalite, and tridymite: Noncrystallinity versus crystallinity, nomenclature of the silica minerals and bibliography

1998 ◽  
Vol 13 (1) ◽  
pp. 2-19 ◽  
Author(s):  
Deane K. Smith
Keyword(s):  
Long Range ◽  
Short Range ◽  
Short Range Order ◽  
Crystalline Silica ◽  
Range Order ◽  
International Agency ◽  
X Ray ◽  
Industrial Operations ◽  
Materials Used ◽  
Ray Patterns

Cristobalite and tridymite are distinct forms of crystalline silica which, along with quartz, are encountered in industrial operations and industrial products. Because the International Agency for Research on Cancer has designated “crystalline silica” as an IARC Group 2A (probable carcinogen) and quartz and cristobalite as a Group 1 (carcinogen), it is important to properly identify and quantify the silica phase in all materials used in production and encountered in products. Opal is a form of hydrated silica which is also encountered in industry. Although some forms of opal mimic cristobalite and tridymite, they are not truly crystalline. The term “silica” in the industrial sense is used to mean any material whose composition is SiO2 whether it is crystalline or noncrystalline. Some people also consider silica to include hydrated SiO2. There are many forms of SiO2 which have both long-range and short-range order and are recognized as crystalline phases among which are quartz, cristobalite, and tridymite. The hydrated silicas, on the other hand, pose an enigma. Only a few forms show sufficient long-range and short-range order to be considered crystalline. The mineral silhydrite is an example. Opal in all its forms lacks sufficient order to be considered crystalline. Even opal-C, which produces a X-ray pattern similar to the diffraction pattern of cristobalite, lacks not only sufficient order to be considered crystalline but also contains water in the structural make-up. This paper discusses a classification and nomenclature for these forms which is critical to proper regulation. It also reviews the recent literature on tridymite, cristobalite, and opal, and provides an extensive bibliography. Modern studies have shown that opal-A is disordered, but opal-CT and opal-C contain ordered domains that mimic stacked sequences of cristobalite and tridymite sheets such that X-ray patterns show features similar to the crystalline cristobalite and tridymite. There is debate on whether the ordered regions have lost the water that characterizes the opals. In fact, heating studies have shown that all opals show changes on heating characteristic of materials that lose water in the process. The TEM evidence showing domains in the range 10–30 nm in a matrix of disordered opal suggest that the proper term for this system is paracrystalline analogous to inorganic and organic polymers.

scholarly journals Long-range ordering in anodic alumina films: a microradian X-ray diffraction study

2010 ◽  
Vol 43 (3) ◽  
pp. 531-538 ◽  
Author(s):  
Kirill S. Napolskii ◽  
Ilya V. Roslyakov ◽  
Andrey A. Eliseev ◽  
Andrei V. Petukhov ◽  
Dmytro V. Byelov ◽  
...  
Keyword(s):  
Diffraction Study ◽  
Long Range ◽  
Film Growth ◽  
Orientational Order ◽  
Anodic Alumina ◽  
X Ray Diffraction ◽  
X Ray ◽  
Alumina Films ◽  
Self Organized ◽  
Long Range Ordering

A quantitative analysis of long-range order in the self-organized porous structure of anodic alumina films has been performed on the basis of a microradian X-ray diffraction study. The structure is shown to possess orientational order over macroscopic distances larger than 1 mm. At the same time, the interpore positional order is only short-range and does not extend over more than ∼10 interpore distances. These positional correlations are mostly lost gradually rather than at the domain boundaries, as suggested by the divergence of the peak width for the higher-order reflections. In the direction of the film growth the pores have a very long longitudinal self-correlation length of the order of tens of micrometres.

A Thermal Study of Al-Pillared Montmorillonites

2011 ◽  
Vol 187 ◽  
pp. 112-116 ◽  
Author(s):  
Hong Yan Xu ◽  
Xing Tong Chen
Keyword(s):  
Atmospheric Pressure ◽  
Layer Structure ◽  
Hydrothermal Stability ◽  
Basal Spacing ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Naturally Occurring ◽  
Pillared Montmorillonites ◽  
Long Range Ordering

Al-pillared montmorillonites (Al-MMT) were synthesized from naturally occurring sodium montmorillonite through exchange of interlamellar ions with hydroxyalumina polycations. Furthermore, Powder X-ray diffraction (XRD), Fourier transformation infra-red spectra (FTIR), Thermogravimetric analysis (TG), and differential scanning calorimetry (DSC) were applied in order to study the themal stability, hydrothermal stability and synthesis mechanisms of pillared materials. The Al-MMT are thermally stable and hydrothermal stability up to700°C. X-ray diffractograms of Al-MMT calcined at 700 0C show a sharp and intense d001 peak, corresponding to a basal spacing of 1.66nm. Until calcinations at 8000C, the pillared clays generally retain their structural ordering as evidenced by a broad basal (001) peak, which is an indication that the layer structure lost some long-range ordering. In a 100% steam flow under atmospheric pressure at 7000C, the characteristic d001 spacing of Al-MMT decreases from 1.83nm to 1.71nm, intensity of basal peak reduced by58%. However, after hydrothermal at 8000C, the basal (001) peak is not observed, indicating a complete structural collapse. Synthesis mechanisms for Al-MMT are established. Some of tetrahedral silicons or aluminums inverse towards gallery to react with pillaring agents and yield Alp-O-AlsⅣ or Alp-O-Sis bridges which would firmly fix the pillars to the host clay.

scholarly journals Kinetic and structural aspects of tantalum hydride formation

2003 ◽  
Vol 68 (8-9) ◽  
pp. 657-663 ◽  
Author(s):  
B.R. Simonovic ◽  
Slavko Mentus ◽  
Radovan Dimitrijevic
Keyword(s):  
Kinetic Parameters ◽  
Hydrogen Pressure ◽  
Room Temperature ◽  
Orthorhombic Symmetry ◽  
X Ray ◽  
Hydride Formation ◽  
Different Temperatures ◽  
Long Range Ordering ◽  
Ray Patterns ◽  
Structural Aspects

Tantalum hydrides of various composition were synthesized by equilibrating tantalum with hydrogen at six different temperatures from 573 to 823 K under a constant hydrogen pressure of 1 bar. Both the exact Ta/H mole ratios and the kinetic parameters of hydriding were determined on the basis of the dependence of the H/Ta mole ratio on time. The influence of stoichiometry on the appearance of X-ray powder diffractograms at room temperature was studied. As a consequence of hydriding, for ratios H/Ta > 0.2, the original bcc Ta-lattice undergoes distortion, manifesting itself as both a shift and a splitting of the X-ray patterns in the X-ray diffractograms. For samples with H/Ta < 0.2, the appearance of some superstructure reflections at low Bragg angles was noted, which suggests a long range ordering of hydrogen with orthorhombic symmetry.

PbI2–TiO2 Bulk Heterojunctions with Long-Range Ordering for X-ray Detectors

2021 ◽  
pp. 11176-11181
Author(s):  
Quan Wen ◽  
Wenbo Ma ◽  
Yujing Liu ◽  
Xinyi Jin ◽  
Jie Ren ◽  
...  
Keyword(s):  
Long Range ◽  
Bulk Heterojunctions ◽  
X Ray ◽  
Long Range Ordering
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