X-ray Powder Diffractograms Research Articles

High temperature synthesis and characteristics of Al-substituted iron alkoxide

A crystalline solid identified as Al-substituted iron alkoxide is obtained from the reaction at 246° C of glycerol with synthetic Al-bearing goethite, when the latter's composition is: Fe 0.904Al 0.096 OOH. X-ray powder diffractograms (XRD) of this solid show a significant shift of the d spacings in comparison to a previously reported pure iron glycerate complex derived from synthetic α-FeOOH. The composition of the metallic alkoxide, calculated from chemical analysis data is: [(C 3H 5O 3Fe 0.98Al 0.02)] n . When this powder is calcined at 1000°C, well-crystallized Al-substituted hematite is produced, whose XRD patterns indicate a shift of the characteristic hematite lines to lower values. The partial (isomorphic) substitution of Fe by Al may also be ascertained from the hydrolysis of the [(C 3H 5O 3Fe 0.98Al 0.02)] n complex by boiling water; then the XRD and chemical analyses of the resulting product show limited formation of a spinel solid solution. In contrast, hydrolysis of pure iron alkoxide yields high amounts of ferrimagnetic spinel (mainly FeO·Fe 2O 3). Some characteristics of the Al-substituted iron alkoxide and of its hydrolysis and calcination products are briefly examined.

High pressure synthesis and characterization of molybdenum disulphide

Polycrystalline molybdenum disulphide has been grown by high pressure (about 54.88 × 10 6 N m −2) reduction of molybdenum trisulphide and characterized by various physicochemical methods. The chemical analysis of the compound established a sulphur to molybdenum ratio of 2, which was also confirmed by thermogravimetric analysis in air. The X-ray data was found to be consistent with 2H-MoS 2, n-type conductivity ( S = −275 μV °C −1) and diamagnetic behaviour ( χ m = −0.049 × 10 −6 c.g.s. e.m.u.). It is a semiconducting material with a room temperature conductivity of of 1.2 × 10 −4 Ω −1 cm −1 and an activation energy of 0.124 eV in the temperature range 150–300 K. A band gap of 0.95 ± 0.02 eV was found from optical absorption studies on a thin MoS 2 film. Thermal studies of MoS 2 in an argon atmosphere has shown its stability up to 1200 °C and thereafter it decomposes to Mo 2S 3. A model has been proposed which describes the thermal behaviour of MoS 2 when heated at various temperatures up to 1200 °C and is based on the appearance of lines in X-ray powder diffractogram of the product resulting from the crystallization of MoS 2. Scanning electron microscope studies have also been made.

X-ray diffraction and ice nucleation studies of Agl-AgBr-Cul system

Lattice parameter calculations and ice nucleation studies for the Agl-AgBr-Cul system are reported in this study. Thirteen samples of different molar compositions were prepared by vacuum fusion. The X-ray powder diffractograms of these samples revealed the formation of cubic solid solutions of the above system. It is found that the 50:25:25 mol% composition of Agl, AgBr and Cul, has the highest nucleation temperature of −0.48° C, which is far greater than −2.53 and −2.26° C for pure Agi and Cul, respectively.

X-ray powder diffractograms of some oligo- and poly(1,1'-ferrocenylene)s

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTX-ray powder diffractograms of some oligo- and poly(1,1'-ferrocenylene)sEberhard W. Neuse and Stewart HartCite this: Macromolecules 1986, 19, 2, 479–481Publication Date (Print):February 1, 1986Publication History Published online1 May 2002Published inissue 1 February 1986https://doi.org/10.1021/ma00156a043RIGHTS & PERMISSIONSArticle Views61Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (457 KB) Get e-Alerts Get e-Alerts

Sorption of Ammonia/Ammonium Ion on Crystalline Hydrous Titanium Dioxide Fibers

Abstract The sorption of ammonia/ammonium ion has been studied on crystalline hydrous titanium dioxide fibers with a layer structure, which are prepared from potassium tetratitanate (K2Ti4O9). From the measurement of the distribution coefficient, it was found that this material strongly preferred ammonium ion to sodium ion. The results of the pH titration curves indicated that this material showed a wide range of acidities toward ammonia/ammonium ion and had 2.63 mequiv/g of an apparent capacity which was about a half of the theoretical ion-exchange capacity. The characterizations of the ammonium adsorbed solid phase at various loading levels were carried out by measuring the X-ray powder diffractograms and the water contents. From these studies, it was concluded that the sorption-desorption reaction of ammonia/ammonium ion on this material took place almost reversibly in three stages.

Transmission Electron Microscope Study of Illite/Smectite, at GCO/DOE 1 Pleasant Bayou Geopressured Geothermal Test Well, Brazoria County, Texas: ABSTRACT

Six shale samples, two from core and four from hand-picked cuttings, were examined by transmission electron microscopy (TEM) techniques to study the effects of burial metamorphism on mixed-phase illite/smectite (I/S). TEM lattice fringe images from shallower samples show mixed-phase End_Page 1211------------------------------ I/S layers in subparallel orientations relative to each other, commonly with branching and interfingering relationships. Electron diffraction patterns of these shallower samples show very diffuse basal reflections, prominent turbostratic structure, pronounced streaking along z*, and multiple z* orientations in the same diffraction pattern. All of these features indicate a poorly defined interstratification of the mixed-phase I/S: the diffuse basal reflections are probably due to the presence of only a few layers in a diffraction position; the turbostratic structure is due to misalignment of individual layers relative to each other; the z* streaking is due to stacking disorders of the layers in a direction perpendicular to the layers; and the multiple z SUP>* orientations are due to rotational disorder of the layers about an axis parallel with the layers. TEM lattice fringe images from deeper samples show mixed-phase I/S layers arranged in a more parallel fashion, with less branching and interfingering. Electron diffraction patterns for these deeper samples show well-defined basal reflections, and both turbostratic structure and z* streaking are less pronounced. These relationships indicate a more regular interstratification for deeper layers: more layers are in diffraction position, the misalignment of individual layers is less evident, and the stacking disorder perpendicular to the layers is less pronounced. X-ray powder diffractograms have been interpreted to indicate ordering of illite and smectite layers within the mixed-phase I/S. This order is first observed below the soft geopressure boundary (0.465 psi/ft) and is prominent below the hard geopressure boundary (0.7 psi/ft). However, neither the TEM lattice fringe images nor the electron diffraction patterns show ordering of illite and smectite layers within mixed-phase I/S. End_of_Article - Last_Page 1212------------

The system graphite-MnCl 2-AlCl 3 Kinetics, structure and mechanism of formation

Graphite-MnCl 2-AlCl 3 intercalation compounds have been prepared via MnCl 2-AlCl 3 complexes. First stage compounds are eventually formed at both 325 and 500°C; products formed at the lower reaction temperature are richer in Mn (C 5.95MnCl 2(AlCl 3) 0.21) than those at 500° (C 7.15MnCl 2(AlCl 2.5) 0.3). At 325° the mechanism is a quasi-selective intercalation of AlCl 3 to the second stage followed by insertion of MnCl 2 to a mixed stage I compound, and finally an isostage Mn enrichment with Al depletion. At 500°, insertion proceeds differently. Rate limiting reactions at each temperature are proposed. Powder X-ray diffractograms give I c = 9.51 A ̊ for Mn-rich first stage compounds. Comparison of calculated and observed (00 l) structure factors gives an Mn-Cl spacing of 1.46 Å as in the pure dichloride. Analysis of ( hkl) positions and the (10 l) and (11 l) intensities of the inserted MnCl 2 indicate an intercalant superlattice with a 0 = 3.69 A ̊ and c 0 = 3 × I c = 28.53 A ̊ . First stage compounds prepared at 500° are considerably less ordered. Results obtained at 325° are especially significant in that 1. (1) this represents the lowest temperature at which dichlorides have been intercalated to rich stages, and 2. (2) long-range (i.e. 3-dimensional) ordering has been documented in a dichloride intercalation compound for the first time, and is sensitive to reaction temperature.

Infrared Spectroscopic Study of Adsorbed Water on Reduced-Charge Na/Li-Montmorillonites

AbstractInfrared (IR) spectra in the fundamental and near-IR regions were obtained for Na-saturated Wyoming montmorillonite and reduced-charge Na/Li-saturated Wyoming montmorillonites hydrated under water vapor at 50% RH and dehydrated under vacuum. For the Na-montmorillonite, changes in the intensities of the structural OH-bending modes, particularly that of the MgAlOH group, were observed as the clay was dehydrated. This result was interpreted as evidence that exchangeable Na ions lose solvation water and settle into the ditrigonal cavities on the clay surface as it becomes desiccated. For the Na/Li-montmorillonites, the structural OH-bending modes also decreased in IR intensity because of Li+ migration into the octahedral sheet. The fundamental IR spectra of D2O adsorbed by the montmorillonites showed characteristic absorptions at 2685, 2510, 2400, and 1205 cm-1 that decreased in intensity proportionally to the cation-exchange capacity. This result, along with corroborating data from X-ray powder diffractograms and from near-IR diffuse reflectance spectra of H2O adsorbed by the clays, suggest that the exchangeable cations on Na-montmorillonite dissociated from the clay surface as it hydrated and played a significant role in organizing the structure of adsorbed water at low water contents.

Dimorphism in triple orthovanadates MIILaTh (VO 4) 3 ( MII = Sr or Pb)

Triple orthovanadates, SrLaTh(VO 4) 3 and PbLaTh(VO 4) 3 are found to be dimorphic, the crystalline form depending upon the firing temperature. The low-temperature form has zircon structure and the corresponding high-temperature form exhibits its well-known monoclinic modification. The X-ray powder diffractograms and infrared spectra are recorded and discussed in comparison with those of structurally related compounds.

Mechanoformation of ammonium perchlorate-potassium perchlorate solid solutions

Ammonium perchlorate-potassium perchlorate mixtures, upon pelletization, form a series of homogeneous solid solutions as manifested by X-ray powder diffractograms. Scanning electron microscopic studies throw light on the mechanism of the solid-solution formation. Solid solutions of ammonium perchlorate-potassium perchlorate have also been obtained by a modified cocrystallization technique. The thermal and combustion behavior of the solid solutions have also been studied, using the DTA technique and the Crawford strand burner.

Etudes structurales et optiques des phases du type Cd 2A 3X (A = As, P; X = Cl, Br, I) et de leur solution solide

The structure of the compounds with general formula Cd 2A 3X (A = As, P; X = Cl, Br, I) was found from X-ray powder diffractograms. The variation of the cell parameter in Cd 2As 3−xP xI solid solution was studied. The basic transition energy as well as its variation with temperature was obtained from transmission spectra on monocristals. Both results are discussed.

ChemInform Abstract: COMPLEXES OF NICKEL(II) AND COPPER(II) HALIDES, NITRATES AND THIOCYANATE WITH RACEMIC 1‐AMINO‐2‐PROPANOL AS A LIGAND

AbstractDie hygroskopischen Ni‐ und Cu‐Komplexe (I) werden durch Behandlung einer mit Triethylorthoformiat dehydratisierten Lösung der entsprechenden Metallsalze in Ethanol mit stöchiometrischen Mengen des Titelliganden erhalten (keine Ausb.‐Angaben).

Natural Occurrence of Feroxyhite (δ′-FeOOH)

AbstractFeroxyhite (δ′-FeOOH) in association with goethite and lepidocrocite was found as a dominant mineral in some rusty precipitates from Finland. These precipitates formed in the interstices of sand grains from rapidly flowing, Fe(II)-containing water which was very quickly oxidized as it flowed through the sediment. The mineral is distinguished from other FeOOH forms and from ferrihydrite mainly by its X-ray powder diffractogram. Further characteristics are an acicular morphology (possibly thin, rolled plates), an internal magnetic field at 4°K of ∼510 kOe, Fe-OH stretching bands at ∼2900 cm−1 and Fe-OH bending bands at 1110, 920, 790, and 670 cm−1, and an oxalate solubility between ferrihydrite and goethite or lepidocrocite. Feroxyhites with very similar properties were synthesized by oxidation of an Fe(II) solution with H2O2 at a pH between 5 and 8.

Kaolin From The Original Kauling (Gaoling) Mine Locality, Kiangsi Province, China

AbstractAlthough the specific outcrop from which the original kaolin at Kauling (Gaoling) Mine, China, was collected cannot now be relocated, samples were collected and studied from the mine tunnel, country rock, and pegmatite which constitute the sources of kaolin in this region. The kaolin is a residual product of weathering. Where the parent rock was a granite the clay is a mixture of platy and elongate kaolin-group minerals, whereas from the pegmatite portion of the parent rock it is halloysite(10Â) with elongate morphology. These mineral identifications are based on X-ray powder diffractograms, scanning electron micrographs, differential thermograms, and an infrared spectrum hitherto not documented for material from this area.Although the Kauling locality is the region for which kaolin is named, the mineral kaolinite is a defined species without a specific type locality. The 11th century Chinese locality was not mentioned in the two classic research papers defining kaolinite. The data on the Chinese kaolin, therefore, cannot be used directly to provide criteria for sharply differentiating the otherwise vague boundary between the minerals kaolinite and halloysite(7Å). Pertinent questions on these kaolin-group mineral relationships are brought into clearer focus.

Thermal behaviours of sulphur-selenium mixtures

The thermal behaviours of sulphur, selenium and their mixtures have been studied over the range 40–450‡. It has been shown that the polymerization threshold temperature of sulphur,TO, decreases with increasing selenium content and follows the equilibrium copolymerization model proposed by Tobolsky and Owen. The formation of octa-atomic species Se8−xSx, where 8 >x > 4, takes place only after sulphur is in the liquid state. The rate of polymerization is enhanced by the addition of increasing amounts of selenium and this is reflected in the higher polymerization peak temperatures. The X-ray powder diffractograms show that all the sulphur-selenium melts belong to the same phase as that of SeS, though the constituent atoms are randomly distributed.

Effects of Micro-Sized Mixtures of Kaolin Minerals on Properties of Kaolinites

Abstract“Kaolinites” from classic, large deposits of kaolin are shown commonly in scanning electron micrographs to be mixtures, at least in part, in microdimensions, of kaolin-mineral polymorphs.Artificial mixtures of selected kaolin polymorphs simulating the natural mixtures, also micrographed, show crystallinities intermediate between the crystallinities of the end members in X-ray powder diffractograms. Thus, apparent crystallinity interpreted from diffractograms of a kaolin specimen may be a product of kaolin-mineral mixture in microdimensions as well as from ordering in the crystals. Evaluation of the crystallinity of a kaolin from powder diffraction may be suspect if independent means, such as SEM, are not used to assess the monomineralic character of that kaolin specimen.Analogous to the apparent crystallinity of a “kaolinite” being the product of a mixture, so may other widely ranging properties of “kaolinite” be products of kaolin-mineral mixtures in microdimensions. These properties include DTA, IR, chemical composition, free energies of formation, and industrial applications.Specifications for a monomineralic, nearly ideal kaolinite are considered—the Keokuk geode variety possesses desired crystallographic and chemical properties.

Mixed Tetrahalocobaltates(II)

Some new mixed tetrahalocobaltates(II of the general formula A2[CoX 2Y 2 where A = (C 2H 5 4N 4 and X and Y = Cl, Br, I, have been isolated and characterized by their chemical analyses, far i.r. spectra, magnetic moments and X-ray powder diffractograms. In all the complexes, Co(II has been found to be tetrahedrally surrounded by halogens.

Cristobalite Morphology and Oxygen Isotopic Composition Variation under Hydrothermal Alteration

AbstractFrom 2 to 28% opal-cristobalite was isolated from the 2–20 µm fraction of rhyolitic and andesitic tuffaceous pyroclastics from the Island of Honshu, Japan, where it had been formed in hydrothermal springs at temperatures of ∼25–170°C as calculated from the oxygen isotopic ratios (18O/16O). Three of the isolates gave X-ray powder diffractograms with strong peaks at 4.07 Å. Two of these also had very weak peaks at 4.32 Å indicative of the presence of traces of tridymite. The fourth isolate had a strong 4.11 Å cristobalite peak and a very weak 4.32 Å peak. The morphology, determined by the scanning electron microscope, varied with the formation temperature indicated by the oxygen isotopic ratio (δ18O), from spheroidal and spongy for the opal-cristobalite formed at ∼25°C (δ18O = 26.0‰) in contrast to angular irregular plates and prisms for that formed at ∼115°C (11.9‰), ∼135°C (7.9 ‰) and ∼170°C (6.8 ‰). The differences in δ18O values are attributed to variation in hydrothermal temperature, but some variability in oxygen isotopic composition of the water is possible. The field-measured temperatures related roughly with the calculated fractionation temperatures except in one site, while the contrast in cristobalite morphology related well to calculated low and high fractionation temperatures. Low-cristobalite of hydrothermal origin in New Zealand (δ18O = 9‰) had characteristic rounded grains with some evidence of platiness. Co-existing quartz grains (δ18O = 10‰) showed more subhedral and irregular prismatic morphology.

Scan Electron Micrographs of Kaolins Collected from Diverse Origins—III. Influence of Parent Material on Flint Clays and Flint-Like Clays

AbstractThe nature of the parent material from which flint clay or flint-like clay is derived may modify the texture of the clay as observed by SEM. Flint clays occurring in Pennsylvanian-age swamp basins into which were transported residues weathered from sedimentary country rock exhibit a texture of interlocked kaolin pockets and sheaves. On the other hand, flint clay or flint-like clay derived by weathering of volcanic ash exhibits a texture resembling, on a micro-scale, the scalloped, “oak-leaf” pattern of montmorillonite. The interpretation is that an expanding clay having a transitional role between the ash and the kaolinite is the donor source of the micro-scalloped pattern inherited by kaolinite. X-ray powder diffractograms of the clays support the interpretation.

Thermal Dehydration Reactions of Bivalent Transition Metal Malonate Dihydrates in Solid State

Abstract The kinetics of the thermal dehydration reactions of MC3H2O4·2H2O(M=Mn(II), Fe(II), Co(II), Ni(II), and Zn(II)) were studied by the Freeman-Carroll and Coats-Redfern methods on the basis of the TG and DTG in nitrogen. The most reasonable reaction order for all the salts was found to be 2/3, indicating that the rate is controlled by the chemical process at a phase-boundary. This was also confirmed by the microscopic observations. The values of activation energy and frequency factor were 70–90 kJ mol−1 and 107–1010 s−1, respectively. The enthalpy changes for all the salts were determined to be 60–80 kJ mol−1 by the DSC measurements. The X-ray powder diffractograms, infrared absorption and diffuse reflectance spectra of the hydrates and anhydrous salts were also examined to obtain informations on their crystal and bonding structures.