Electron diffraction kaolinite

In addition to those minerals associated with the granular constituent, there are numerous submicron-sized minerals that are intimately mixed with other coal macerals. A typical example can be seen in Figure 11, which is a TEM micrograph of vitrinite, where the circular aperture identifies the region from which the electron diffraction pattern, shown in the inset, was obtained. The mineral, which was identified as kaolinite, appears to have been deposited as plates parallel with the coal bedding, based upon an analysis of the diffraction pattern. Also present in these coals is the clay mineral illite, which can be distinguished from kaolinite by both EDX and SAD analyses, lllites contain potassium (K)... 

Shortly after these conclusions by Brindley and Nakahira, the Russian worker Zvyagin [1960] published an electron diffraction study of the structure of a single crystal of kaolinite. This was followed within a few months by Drits and Kashaev [1960], who reported on an X-ray diffraction study of a single crystal. These studies essentially confirmed the work of Brindley and Nakahira. 

Zvyagin [1967] is convinced that the halloysite structure is not merely disordered kaolinite. When the degree of disorder is great in either kaolinite or halloysite, there is little to distinguish between the two minerals, but the stacking sequence of the layers in halloysite cannot be derived from that of kaolinite. Souza Santos et al. [1965] have also commented that dried fiber bundles of halloysite from Brazil show some degree of regularity in their structures when examined by X-ray diffraction and selected-area electron diffraction. 

In order to substantiate further the mineral matter content information received from the x-ray diffraction analyses, several coke pellets were scanned for sulfur, iron, calcium, silicon, aluminum and potassium in the electron microprobe. Electron probe results showed abundant silicon, suggesting quartz (Si02), considerable aluminum, suggesting kaolinite [Ali>Sii Oii(OH)4] and, relatively speaking, little iron, sulfur, calcium, or potassium. 

The amount of adsorbed metal was determined by the weight difference of the pre-and post-sorption sorbent. The structural and morphological change of kaolinite granules during sorption tests was investigated by the powdered X-ray diffraction (XRD) analysis (Philips, X pert MPD) and scanning electron microscopy (SEM) (JEOL, JXA 8600). 

Many of the fine minerals shown previously in Figure 7 can be seen to be randomly oriented in fact, some of the platy minerals are found to be perpendicular to the layering. SAD experiments on some of the larger mineral plates typical of those shown in Figure 12 resulted in diffraction patterns of the type shown in the inset. The pattern was indexed as the (hkO) plane of kaolinite, indicating that the electron beam is parallel to the c-axis of the crystal. 

The minerals found in United States coals continue to be studied with the availability of improved instrumental procedures such as x-ray diffraction, infrared absorption, and scanning electron microscopy beyond the traditional optical and chemical mineralogical techniques as applied to thin sections, polished pellets, and isolated particles. The minerals may be grouped into the silicates (kaolinite, illite montmorillonite, and chlorite), the oxides (quartz, chalcedony, hematite) the sulfides (pyrite, marcasite, and sphalerite) the sulfates (jarosite, gypsum, barite, and numerous iron sulfate minerals) the carbonates (ankerite, calcite, dolomite, and siderite) and numerous accessory minerals (apatite, phosphorite, zircon, rutile, chlorides, nitrates, and trace minerals). 

The clay minerals used in this study were kaolinite (AI281205(OH) ), illite (Kj A1jSi2+ (OH)2), and montmorillonite which was approximately 1/2 (Ca, Na)Q (Al, Mg, Fe) (Si, ADqO q (OH). n H2O. The clays were natural samples purchased from Ward s Natural Science Establishment, Inc. The kaolinite sample was obtained from a kaolin deposit in Georgia. X-ray diffraction (XRD) patterns on this material showed peaks only for kaolinite, and scanning electron micro-scope-energy dispersive x-ray (SEM-EDX) analysis yielded peaks for Al, Si, and minor amounts of Ti. The illite was a green shale from New York which Ward s listed as 85% illite. XRD patterns of this... 

Keywords Metal nanoparticles Kaolinite Adsorption Transmission electron microscopy X-ray diffraction Small-angle X-ray scattering... 

The distinction between kaolinite and halloysite can be difficult. Even when techniques of X-ray diffraction, differential thermal analysis, electron microscopy, and chemical treatments are combined, the result may still be doubtful. If hydrated halloysite is present, it can be detected by a basal spacing of 7.3 A or larger, which shifts to smaller spacings when the sample... 

If much well-ordered kaolinite is present, the assymmetric peaks are not prominent in the patterns from random samples, and the basal reflections are sharper and much enhanced in intensities in patterns from oriented samples. If much disordered kaolinite is present, the assymmetric peaks are prominent in the first patterns, and the basal reflections are much enhanced in the second. Chemical pretreatments prior to X-ray diffraction, such as those proposed by Wada [1965] and Alexiades and Jackson [1965], are sometimes useful in determining amounts of kaolinite and halloysite. Where the halloysite is tubular, it is easily detected in electron micrographs, although the amount can seldom be determined. Amounts of hydrated halloysite can be determined if allophane is not present in differential thermal analysis by calibrating and measuring the low-temperature endothermic peak. 

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