X-ray diffraction characteristics and related properties of Smectites in some Canadian soils

1993 ◽  
Vol 73 (1) ◽  
pp. 93-102 ◽  
Author(s):  
G. J. Ross ◽  
H. Kodama
Keyword(s):  
Exchange Capacity ◽  
X Ray Diffraction ◽  
Diffraction Intensity ◽  
Eastern Canada ◽  
X Ray ◽  
Podzolic Soils ◽  
Peak Intensity ◽  
Soil Clays ◽  
Canadian Soils ◽  
Particle Thickness

The X-ray diffraction (XRD) peak intensities of smectites in Chernozemic and related soils of Western Canada are generally low, in contrast to the high peak intensities of smectites in Podzolic soils of Eastern Canada and those of standard smectite samples. Consequently, X-ray quantitative analysis based on standard smectite samples may underestimate the amount of smectite and overestimate the amount of noncrystalline material in western Canadian soils. This study was undertaken to find the reasons for the weak XRD peak intensities of western soil smectites in terms of their purity and crystallinity. The Tiron dissolution method extracted only small amounts of noncrystalline material from the western soil clays and had little effect on XRD characteristics. The cation exchange capacity (CEC) hysteresis (or pH dependent CEC) between pH 3.5 and 11.0 of the western soil clays was also relatively small which confirmed the absence of significant amounts of noncrystalline material in these soil clays. Observed deviations of XRD positions from true basal spacings indicated that the western soil smectite particles were consistently thinner than the eastern soil smectite and Wyoming montmorillonite particles. Electron microscope observations supported these results. Because the diffraction intensity is proportional to the square of the particle thickness, the thinness of the western soil smectite particles appears to be a major factor in reducing their peak intensities. Thus, to obtain comparable peak intensity data from different soil smectites, particle thickness should be taken into account. Since it is often not practical to measure particle thickness, a procedure for quantifying smectite in soils that avoids this measurement is proposed. Key words: Peak intensity, crystallinity, particle size, particle thickness, Chernozemic smectite, Podzolic smectite

OCCURRENCE AND DETERMINATION OF LEPIDOCROCITE IN CANADIAN SOILS

1979 ◽  
Vol 59 (2) ◽  
pp. 155-162 ◽  
Author(s):  
G. J. ROSS ◽  
N. M. MILES ◽  
H. KODAMA
Keyword(s):  
Acid Soils ◽  
Chemical Dissolution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Shape Characteristic ◽  
Soil Clays ◽  
Canadian Soils ◽  
Soluble Aggregates ◽  
Diffraction Patterns

Lepidocrocite occurred in B and C horizons of several poorly drained, acid soils; it was determined by X-ray diffraction, electron optical, and chemical dissolution methods. A comparison of X-ray diffraction results obtained by diffractometer, Debye-Scherrer and Guinier-de Wolff methods showed the latter method to be superior in providing the more distinct and complete evidence of lepidocrocite in soil clays. Dithionite-soluble aggregates commonly had a dumbbell-like shape characteristic of lepidocrocite but their electron diffraction patterns were similar to those of maghemite. This suggested the topotactic dehydroxylation of lepidocrocite in the electron microscope. Amounts of lepidocrocite estimated from X-ray diffraction intensities agreed fairly well (within 2.5%) with amounts calculated from iron dissolved by dithionite and oxalate treatments. Lepidocrocite concentrations in soil clays of 1–2% gave distinct X-ray diffraction evidence.

The soil clays of Great Britain: I. England and Wales

Clay Minerals ◽  
1984 ◽  
Vol 19 (5) ◽  
pp. 681-707 ◽  
Author(s):  
P. J. Loveland
Keyword(s):  
Soil Mechanics ◽  
Clay Mineralogy ◽  
Soil Surface ◽  
Exchange Capacity ◽  
X Ray Diffraction ◽  
England And Wales ◽  
X Ray ◽  
Soil Clays ◽  
Soil Clay ◽  
Interstratified Mineral

AbstractThe mineralogy of the clay fractions (<2 µm) of the major soils of England and Wales is reviewed, and the data presented in terms of the 1:250 000 National Soil Map. Most soils developed in pre-Rhaetic sediments are dominated by mica with lesser amounts of chlorite and kaolin. Exceptions are soils developed in calcareous Coal Measure shales which have significant smectite contents, and freely drained soils in Keuper Marl which contain swelling chlorite, sepiolite and palygorskite. Soils developed in post-Triassic sediments are dominated generally by expansible minerals, except for those developed in Lower Lias and Estuarine Series rocks (Jurassic) which are dominated by mica and kaolin respectively. The presence of loess in soils seems to be associated with the occurrence of a complex interstratified mineral with X-ray diffraction properties akin to vermiculite. Weathering of soil clays is most marked in the wetter uplands, but over most of lowland England is detectable only by slight changes in non-exchangeable potassium content and cation-exchange capacity towards the soil surface. Applications of soil clay mineralogy in the fields of plant nutrition and soil mechanics are discussed, in particular the production of maps showing mineralogical provinces.

The conversion of smectite to illite during diagenesis: evidence from some illitic clays from bentonites and sandstones

1985 ◽  
Vol 49 (352) ◽  
pp. 393-400 ◽  
Author(s):  
P. H. Nadeau ◽  
M. J. Wilson ◽  
W. J. McHardy ◽  
J. M. Tait
Keyword(s):  
Organic Molecules ◽  
Thickness Distribution ◽  
Sedimentary Rocks ◽  
Exchangeable Cations ◽  
Diffraction Effect ◽  
X Ray Diffraction ◽  
X Ray ◽  
Depth Of Burial ◽  
Particle Thickness ◽  
Scanning Electron

AbstractDiagenetic illitic clays from seven North American bentonites of Ordovician, Devonian, and Cretaceous ages and from three subsurface North Sea sandstones of Permian and Jurassic ages have been examined by X-ray diffraction (XRD) and transmission and scanning electron microscopy (TEM and SEM). XRD indicates that the clays from the bentonites are randomly and regularly interstratified illite/smectites (I/S) with 30–90% illite layers, whereas the clays from the Jurassic and Permian sandstones are regularly interstratified I/S, with 80–90% illite layers, and illite respectively. TEM of shadowed materials shows that randomly interstratified I/S consists primarily of mixtures of elementary smectite and ‘illite’ particles (10 and 20Å thick respectively) and that regularly interstratified I/S and illite consist mainly of ‘illite’ particles 20–50 Å thick and > 50 Å thick respectively. Regularly interstratified I/S from bentonites and sandstones are similar with regard to XRD character and particle thickness distribution. These observations can be rationalized if the interstratified XRD character arises from an interparticle diffraction effect, where the smectite interlayers perceived by XRD, result from adsorption of exchangeable cations and water or organic molecules at the interfaces of particles generally < 50Å thick. A neoformation mechanism is proposed by which smectite is converted to illite with increasing depth of burial in sedimentary rocks, based on dissolution of smectite particles and the precipitation/growth of ‘illite’ particles occurring within a population of thin phyllosilicate crystals.

A high-energy triple-axis X-ray diffractometer for the study of the structure of bulk crystals

2004 ◽  
Vol 37 (6) ◽  
pp. 901-910 ◽  
Author(s):  
C. Seitz ◽  
M. Weisser ◽  
M. Gomm ◽  
R. Hock ◽  
A. Magerl
Keyword(s):  
High Energy ◽  
X Rays ◽  
Bulk Crystals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Peak Intensity ◽  
High Penetration ◽  
Massive Sample ◽  
Laue Geometry ◽  
The Ideal

A triple-axis diffractometer for high-energy X-ray diffraction is described. A 450 kV/4.5 kW stationary tungsten X-ray tube serves as the X-ray source. Normally, 220 reflections of thermally annealed Czochralski Si are employed for the monochromator and analyser. Their integrated reflectivity is about ten times higher than the ideal crystal value. With the same material as the sample, and working with the WKα line at 60 keV in symmetric Laue geometry for all axes, the full width at half-maximum (FWHM) values for the longitudinal and transversal resolution are 2.5 × 10−3and 1.1 × 10−4for ΔQ/Q, respectively, and the peak intensity for a non-dispersive setting is 3000 counts s−1. In particular, for a double-axis mode, an energy well above 100 keV from theBremsstrahlungspectrum can be used readily. High-energy X-rays are distinguished by a high penetration power and materials of several centimetre thickness can be analysed. The feasibility of performing experiments with massive sample environments is demonstrated.

Quantitative Phase Analysis By Linear Regression of Chemistry on X-Ray Diffraction Intensity

1987 ◽  
Vol 2 (2) ◽  
pp. 96-98 ◽  
Author(s):  
Jacques Renault
Keyword(s):  
Linear Regression ◽  
Quantitative Information ◽  
Quantitative Phase Analysis ◽  
X Ray Diffraction ◽  
Diffraction Intensity ◽  
Mineralogical Analysis ◽  
X Ray ◽  
Reduction Program ◽  
Speed Of Analysis ◽  
Artificial Mixtures

AbstractXRF and XRD measurements made on a single pressed powder briquet can be combined to give more quantitative information than either technique employed alone. Speed of analysis and simplification of sample preparation are also enhanced. The algorithm presented here uses multiple linear regression of the concentrations of one or more elements on the corrected X-ray diffraction intensities of the phases containing them. The data reduction program runs on a microcomputer. Data are presented to show its application to mineralogical analysis of artificial mixtures of quartz, microcline (a feldspar) and calcite.

Interdiffusion in Co/Ta Multilayer Thin Films

2005 ◽  
Vol 237-240 ◽  
pp. 554-559 ◽  
Author(s):  
Hui Myeong Lee ◽  
Byeong Seon Lee ◽  
Chan Gyu Lee ◽  
Yasunori Hayashi ◽  
Bon Heun Koo
Keyword(s):  
Structural Relaxation ◽  
Multilayer Thin Films ◽  
X Ray Diffraction ◽  
Stress Release ◽  
X Ray ◽  
Angle Measurements ◽  
Peak Intensity ◽  
Straight Line ◽  
Initial Stage ◽  
Interdiffusion Coefficients

We will discuss the stress release phenomena, structural relaxation and interdiffusion processes during annealing. The [Co(4nm)/Ta(4nm)]38 multilayers were prepared by dc magnetron sputtering on Si substrate. The multilayers were annealed at various temperatures (523 - 673K) in vacuum (under 10-5 torr) furnace. The effective interdiffusion coefficients were determined from the slope of the best straight line fit of the first peak intensity versus annealing time [d ln(I(t)/I(0)) /dt] by X-ray diffraction (XRD) low angle measurements. The drastic decrease of the relative intensity in the initial stage shown due to the structural relaxation was excluded in the calculation of effective interdiffusion coefficients. The temperature dependence of interdiffusion in the range of 523 - 673K is described by D = 3.2×10-19 exp(-0.51±0.11 eV/kT) m2s-1.

Sign in / Sign up

Export Citation Format

Share Document