Interpretation of X-ray Powder Diffraction Patterns . By H. Lipson and H. Steeple. Pp. viii + 335 + 3 plates. (Mac-millan: London; St Martins Press: New York, May 1970.) £4.

X-Ray Diffraction

Phyllosilicates, and among them clay minerals, are of great interest not only for the scientific community but also for their potential applications in many novel and advanced areas. However, the correct application of these minerals requires a thorough knowledge of their crystal chemical properties. This chapter provides crystal chemical and structural details related to phyllosilicates and describes the fundamental features leading to their different behaviour in different natural or technical processes, as also detailed in other chapters of this book. Phyllosilicates, described in this chapter, are minerals of the (i) kaolin-serpentine group (e.g. kaolinite, dickite, nacrite, halloysite, hisingerite, lizardite, antigorite, chrysotile, amesite, carlosturanite, greenalite); (ii) talc and pyrophyllite group (e.g. pyrophyllite, ferripyrophyllite); (iii) mica group, with particular focus to illite; (iv) smectite group (e.g. montmorillonite, beidellite, nontronite, saponite, hectorite, sauconite); (v) vermiculite group; (vi) chlorite group; (vii) some 2:1 layer silicates involving a discontinuous octahedral sheet and a modulated tetrahedral sheet such as kalifersite, palygorskite and sepiolite; (viii) allophane and imogolite and (ix) mixed layer structures with particular focus on illite-smectite.

Structure and Mineralogy of Clay Minerals

Porosity investigation of compacted bentonite using XRD profile modeling.

THE, first meeting of the International Union of Crystallography, which was held at Harvard University during July 28-August 3, provided an opportunity for the presentation of papers on many research projects that are being carried out in different parts of the world. More than seventy such papers were read, and there were many detailed discussions.

/pdf/international-union-of-crystallography-3ebwh76rex.pdf

International Union of Crystallography

We used a suite of techniques, including those emulating compositional data sets obtained from Mars orbit and obtainable at the Mars surface, to examine aqueous alteration of basaltic rocks from Iceland as a mineralogic and geochemical analog for Noachian environments on Mars. A sample suite was collected for laboratory measurement of (1) whole-rock visible/near-infrared (VNIR) reflectance and thermal infrared (TIR) emission spectra; (2) VNIR and TIR reflectance spectra of particle-size separates derived from the bulk rock and from materials extracted from fractures/vesicles; (3) X-ray diffraction (XRD) patterns for determination of quantitative modal mineralogy; (4) major element chemistry using flux fusion of whole-rock powders; and (5) electron microprobe analyses of minerals in thin sections. Conclusions about aqueous alteration can be influenced by technique. For these basalts, whole-rock chemical data showed scant evidence for chemical fractionation, but TIR, VNIR, and XRD measurements identified distinctive assemblages of hydrous silicate minerals, differing by sample. XRD provided the most complete and accurate quantitative determination of sample mineralogy. However, VNIR spectroscopy was the technique most useful for determining composition of low-abundance smectite clays, and TIR spectroscopy was the most useful for recognizing hydrated silicates in thin surface coatings. High spatial resolution mineralogical and chemical data sets were useful for understanding the texture and distribution of alteration products and variations in fluid chemistry. No single approach provides a complete assessment of the environment of alteration, demonstrating the importance of employing multiple, synergistic mineralogical and geochemical techniques and instruments in exploration of rock strata from aqueous paleoenvironments on Mars.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2012JE004156

Mineralogy and chemistry of altered Icelandic basalts: Application to clay mineral detection and understanding aqueous environments on Mars

NEWMOD was developed by R.C. Reynolds, Jr., for the study of two-component interstratifications of clay minerals. One-dimensional X-ray diffraction (XRD) profiles of an interstratified system of two clay minerals can be simulated using NEWMOD, given a set of parameters that describes instrumental factors, the chemical composition of the system (e.g. the concentration of Fe and interlayer cations), and structural parameters (e.g. proportions of the two components, the nature of ordering, and crystallite size distribution). NEWMOD has served as the standard method for quantitatively evaluating interstratified clay minerals for >20 y. However, the efficiency and accuracy of quantitative analysis using NEWMOD have been limited by the graphical user interface (GUI), by the lack of quantitative measures of the goodness-of-fit between the experimental and simulated XRD patterns, and by inaccuracies in some structure models used in NEWMOD. To overcome these difficulties, NEWMOD+ was coded in Visual C++ using the NEWMOD architecture, incorporating recent progress in the structures of clay minerals into a more user-friendly GUI, greatly facilitating efficient and accurate fitting. Quantitative fitting parameters (unweighted R-factor, Rp, weighted R-factor, Rwp, expected R-factor, Rexp, and chisquare, χ2) are included, along with numerous other features such as a powerful series generator, which greatly simplifies the generation of multiple simulations and makes NEWMOD+ particularly valuable for teaching.

NEWMOD+, a new version of the NEWMOD program for interpreting X-ray powder diffraction patterns from interstratified clay minerals

Nodes clustering and multi-hop routing protocol optimization using hybrid chimp optimization and hunger games search algorithms for sustainable energy efficient underwater wireless sensor networks

NEWMOD®, developed by R.C. Reynolds, Jr., has been an important tool for evaluating quantitatively X-ray diffraction (XRD) patterns from interstratified clay minerals for more than 20 years. However, a significant drawback to the NEWMOD® approach is that analyses are done by forward simulation, making results sensitive to user input and starting-model assumptions. In the present study, a reverse-fitting procedure was implemented in a new program, FITMOD, which automatically minimizes the differences between experimental and simulated XRD patterns. The differences are minimized by varying model parameters (such as Reichweite, crystal-size distribution, cation content, type of disorder, etc.) using the downhill simplex method. The downhill simplex method is a non-linear optimization technique for determining minima of functions. This method does not require calculation of the derivatives of the functions being minimized, an important consideration with many of the parameters in NEWMOD- type simulations. Instead, the downhill simplex method calculates pseudo-derivatives by evaluating sufficient points to define a derivative for each independent variable. The performance of FITMOD was evaluated by fitting a series of synthetic XRD patterns generated by NEWMOD+, yielding agreement factors, Rwp, of <0.3%. As long as the correct interstratified system was specified (e.g. illite-smectite), excellent fits were obtained irrespective of the starting parameters for the simulations. FITMOD was also tested using experimental XRD patterns, which gave very good fits, in agreement with previously published results. The optimization routine yields good fits for both synthetic and experimental XRD profiles in a reasonable time, with the possibility of varying all important structural parameters. FITMOD automatically provides optimum fits to experimental XRD data without operator bias, and fitting efficiency and accuracy were, therefore, significantly improved.

Automated fitting of x-ray powder diffraction patterns from interstratified phyllosilicates

Diffraction effects from interstratified phyllosilicates have been studied extensively, and several computer programs such as NEWMOD© are available to facilitate interpretation of X-ray diffraction (XRD) profiles. However, accurate quantification of samples containing multiple interstratified phyllosilicate minerals is difficult due to the generally subjective nature of interpretations. More recent automated fitting interpretations require extensive computational effort, involving numerous calculations of profiles with different fitting-parameter values. Computational cost in time per calculation is the key factor influencing the overall efficiency of automated profile fitting. In general, the matrix methodology developed by Kakinoki and Komura is more efficient than the NEWMOD© architecture. A new matrix methodology was developed that reduces the number of matrix operations such as multiplication and addition, and these modifications improve calculation efficiency by up to a factor of three, with even greater improvement for small crystallite sizes (< 20 layers). A new computer program, ClayStrat, based on the modified matrix methodology, was developed to calculate one-dimensional XRD profiles from interstratified phyllosilicates along the Z direction.

Improved Matrix Methodology for Calculating Diffraction Intensity Profiles from Interstratified Phyllosilicates


 Since particle size distribution (PSD) affects drilling fluid performance, devices for measuring particle size have been widely used in the field and in laboratories. Laser diffraction (also called laser light scattering) is the technique most often employed, because it is easy, rapid, and provides reproducible results. However, variations in laser diffraction instrumentation and operating protocols in different testing facilities/laboratories can cause the PSD results to vary significantly. The problem is serious for water-based drilling fluids, but it can be even more severe for non-aqueous drilling fluids (NADFs) because of variations in base fluid and the presence of emulsified water. To address this, a work group was formed by the American Petroleum Institute (API) to develop a general and robust testing procedure for measuring PSD of NADFs using laser diffraction instruments. After identifying fundamental variables (including sampling method, instrument, sonication treatment, dispersant) that can affect PSD results, pilot testing was carried out with various instruments to determine general operating settings regardless of the specific instrument. Based on these studies, a measurement procedure was developed and evaluated with a round robin test in which five NADFs possessing different base fluids, solids content, and water/oil ratios were measured by several laboratories using different particle sizers. The PSD results of these five fluids measured by different laboratories agreed well, confirming the robustness of the measurement procedure. The developed measurement procedure has been accepted and will be included as a recommended procedure in the API RP 13I 2019 revision. This paper will discuss the development of the procedure and the round robin test results in detail.

Hongji Yuan

Papers

NEWMOD+, a new version of the NEWMOD program for interpreting X-ray powder diffraction patterns from interstratified clay minerals

Nodes clustering and multi-hop routing protocol optimization using hybrid chimp optimization and hunger games search algorithms for sustainable energy efficient underwater wireless sensor networks

Automated fitting of x-ray powder diffraction patterns from interstratified phyllosilicates

Improved Matrix Methodology for Calculating Diffraction Intensity Profiles from Interstratified Phyllosilicates

Robust Procedure for Measuring Particle Size Distribution of Non-Aqueous Drilling Fluids Using Laser Diffraction