Hydration behavior by X-ray diffraction profile fitting of smectite-bearing minerals in a Plio-Pleistocene mudrock from Eugene Island, Gulf of Mexico

2019 ◽  
Vol 102 ◽  
pp. 86-100 ◽  
Author(s):  
Ruarri J. Day-Stirrat ◽  
L. Taras Bryndzia ◽  
Anja M. Schleicher ◽  
Rieko Adriaens ◽  
Ronny Hofmann ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
X Ray Diffraction ◽  
Diffraction Profile ◽  
X Ray ◽  
Profile Fitting

A Gaussian–Hermite polynomials function for X-ray diffraction profile fitting

1999 ◽  
Vol 32 (4) ◽  
pp. 730-735 ◽  
Author(s):  
F. Sánchez-Bajo ◽  
F. L. Cumbrera
Keyword(s):  
Hermite Polynomials ◽  
Gaussian Function ◽  
Shape Functions ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Profile Function ◽  
Diffraction Profile ◽  
X Ray ◽  
Profile Fitting ◽  
Diffraction Peaks

In recent years, several profile-shape functions have been successfully used in X-ray powder diffraction studies. Here, a new profile function for approximating the X-ray diffraction peaks is proposed. This model, based on a Gaussian function multiplied by a correction factor in the form of a series expansion in Hermite polynomials, can be employed in the cases where there are peak asymmetries. The function has been tested by using samples of α-Al2O3and 9-YSZ (yttria-stabilized zirconia), yielding generally satisfactory results.

scholarly journals Hydration behavior by X-ray diffraction profile fitting of smectite-bearing minerals

2020 ◽  
Vol 205 ◽  
pp. 04009
Author(s):  
Ruarri J. Day-Stirrat ◽  
L. Taras Bryndzia
Keyword(s):  
Relative Humidity ◽  
Clay Mineralogy ◽  
Wellbore Stability ◽  
Natural Material ◽  
X Ray Diffraction ◽  
Geological Time ◽  
Diffraction Profile ◽  
X Ray ◽  
Profile Fitting ◽  
Term Creep

Clay mineral hydration and dehydration processes are reversible at temperatures <100 °C and strongly affect wellbore stability, fines migration, permeability, and dispersion of pore pressure. The hydration behavior of smectite-rich material as a function of relative humidity (activity of water, aw, controlled by salinity) and temperature was studied using in situ X-ray diffraction on a material retrieved from coring in the Gulf of Mexico. X-ray diffraction profile fitting was used to explore the competition for water between hydratable phases across a range of relative humidity, 2 % to 90 %, and temperature, 25°C to 95°C, conditions. X-ray diffraction profile fitting employed a modified multi-specimen approach in which proportions of minerals were modelled using Ca-exchanged preparations in air-dried and ethylene glycol solvated states. Across the range of hydration states, the mineral proportions and crystallographic parameters remained constant from the multi-specimen approach and only the number of water layers in hydratable phases varied. Quantitative clay mineralogy showed a natural material with a discrete smectite component and a mixed-layered illite-smectite, both capable of hydration/dehydration. Results of this study showed the discrete smectite component and the mixed-layered illite-smectite hydrated at different rates with discrete smectite up-taking more water at lower relative humidity than the mixed-layered illite-smectite. Over geological time this study highlights the non-static nature of smectite hydration with implications of long-term creep and permeability behavior.

X-Ray Diffraction Profile Analysis for Characterizing Isothermal Aging Behavior of M250 Grade Maraging Steel

2008 ◽  
Vol 39 (8) ◽  
pp. 1978-1984 ◽  
Author(s):  
S. Mahadevan ◽  
T. Jayakumar ◽  
B.P.C. Rao ◽  
Anish Kumar ◽  
K.V. Rajkumar ◽  
...  
Keyword(s):  
Maraging Steel ◽  
Isothermal Aging ◽  
Profile Analysis ◽  
X Ray Diffraction ◽  
Aging Behavior ◽  
Diffraction Profile ◽  
X Ray

scholarly journals New Insights on the Distribution of Interlayer Water in Bi-Hydrated Smectite from X-ray Diffraction Profile Modeling of 00lReflections

2005 ◽  
Vol 17 (13) ◽  
pp. 3499-3512 ◽  
Author(s):  
Eric Ferrage ◽  
Bruno Lanson ◽  
Natalie Malikova ◽  
Alain Plançon ◽  
Boris A. Sakharov ◽  
...  
Keyword(s):  
X Ray Diffraction ◽  
Interlayer Water ◽  
Diffraction Profile ◽  
X Ray ◽  
Profile Modeling

scholarly journals Soil Development under Continuous Agriculture at the Morrow Plots Experimental Fields from X-ray Diffraction Profile Modelling

Soil Systems ◽  
2018 ◽  
Vol 2 (3) ◽  
pp. 46 ◽  
Author(s):  
Eleanor Bakker ◽  
Fabien Hubert ◽  
Michelle M. Wander ◽  
Bruno Lanson
Keyword(s):  
Cation Exchange ◽  
Relative Proportion ◽  
Mineral Dissolution ◽  
Continuous Cropping ◽  
X Ray Diffraction ◽  
Diffraction Profile ◽  
Size Fractions ◽  
X Ray ◽  
Fine Clay ◽  
Mixed Layers

Impact of continuous cropping on clay mineralogy was assessed on a collection of unfertilized soil samples from the Morrow Plots experimental fields covering 110 years of long crop rotations. Evolution of mineralogy was quantitatively determined by fitting X-ray diffraction (XRD) patterns from four size fractions (50–2, 2–0.2, 0.2–0.05 and <0.05 µm) of the surface horizon (0–20 cm). The mineralogy of the three clay subfractions (2–0.2 µm, 0.2–0.05 µm and <0.05 µm) consists mainly of coexisting illite-smectite-chlorite whose compositions range from discrete illite (in the 2–0.2 µm subfraction) to discrete smectite (in the <0.05 µm subfraction). Mixed layers of similar compositions were used to fit XRD data from all clay subfractions. With decreasing size fractions, both the size of the coherent scattering domains and the proportion of illite-rich mixed layers decrease, thus accounting for the higher cation exchange measured in the <0.05 µm subfraction compared to other clay subfractions. The analysis of fine clay subfractions (<0.2 µm or lower) provided key information and constraints to a complete and accurate description of the bulk <2 µm fraction. Additional constraints derived from chemical treatments (K-saturation and heating) proved to be especially useful to propose a reliable structure model for these fine clay subfractions because of their weakly modulated diffraction signature. Mineralogy of all subfractions considered is essentially stable over the studied period (1904–2014), with the relative proportion of the different clay layer types (illite, smectite, kaolinite, chlorite) showing no significant evolution in the bulk <2 µm fraction. A century of continuous cropping thus results essentially in an increase of fine clay particles (<0.05 µm) and a decrease of the 0.2–0.05 µm subfraction, indicative of clay mineral dissolution and consistent with observed increase of cation exchange capacity with time. The relative proportion of the bulk <2 µm fraction is nearly constant over the studied period, indicative of minimal export of clay phases.

A profile-fitting procedure for analysis of broadened X-ray diffraction peaks. I. Methodology. Erratum

1989 ◽  
Vol 22 (2) ◽  
pp. 184-184 ◽  
Author(s):  
S. Enzo ◽  
G. Fagherazzi ◽  
A. Benedetti ◽  
S. Polizzi
Keyword(s):  
X Ray Diffraction ◽  
Correct Equation ◽  
X Ray ◽  
Fitting Procedure ◽  
Profile Fitting ◽  
Diffraction Peaks

Equation (18) of the paper by Enzo, Fagherazzi, Benedetti & Polizzi [J. Appl. Cryst. (1988). 21, 536–542] is in error. The correct equation is: A(2θ) = exp [−a|(2θ − 2θ 0)/cot 2θ 0|].

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