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Powder Diffraction (powder + diffraction)
Kinds of Powder Diffraction Terms modified by Powder Diffraction Selected AbstractsDETERMINATION OF PIGMENTS AND BINDERS IN POMPEIAN WALL PAINTINGS USING SYNCHROTRON RADIATION , HIGH-RESOLUTION X-RAY POWDER DIFFRACTION AND CONVENTIONAL SPECTROSCOPY , CHROMATOGRAPHYARCHAEOMETRY, Issue 2 2010A. DURAN The employment of synchrotron techniques complemented by conventional laboratory systems has allowed us to deepen and improve our knowledge of Roman wall painting procedures. The palette identified in wall paintings from Pompeii and Herculaneum from the second century bc includes goethite, hematite, cinnabar, glauconite, Egyptian blue, and other components such as calcite and aragonite. Proof of the use of organic binders is provided by FTIR and PY,GC/MS. Therefore, the possibility of the use of ,a secco' techniques cannot be ruled out. Pigments in wall paintings are usually found in small percentages and conventional X-ray diffractometers do not detect them. Synchrotron radiation , high-resolution X-ray powder diffraction has allowed identification with only a few micrograms of sample. [source] Thermal, phase transition and spectral studies in erythromycin pseudopolymorphs: dihydrate and acetone solvateCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2006Zhanzhong Wang Abstract The thermal, phase transition and spectral studies of erythromycin A dihydrate and acetone solvate were performed by Differential Scanning calorimetry (DSC), Thermo Gravimetry (TG-DTA), X-Ray Powder Diffraction (XRPD) and Fourier Transform Infra-Red (FTIR) spectrum. The non-thermal kinetic analysis of erythromycin A dihydrate was carried out by DSC at different heating rates in dynamic nitrogen atmosphere. The result showed that heating rate has substantial influence on the thermal behavior of erythromycin dihydrate. The Arrhenius parameters were estimated according to the Kissinger method. Corresponding to dehydration of dihydrate, melting of dehydrated dihydrate, phase transition from dehydrated dihydrate to anhydrate, and melting of anhydrate, the calculated activation energy were 39.60, 269.85, 261.23, and 582.16 kJmol,1, the pre-exponential factors were 3.46 × 103, 8.06 × 1032, 9.23 × 1030, and 7.29 × 1063 s,1, respectively. Ozawa method was used to compare activation energy values calculated by Kissinger method. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The Microstructure of Biogenic Calcite: A View by High-Resolution Synchrotron Powder Diffraction,ADVANCED MATERIALS, Issue 18 2006B. Pokroy Biogenic calcite obtained from different mollusk shells is subjected to heat treatments at elevated temperatures and structurally analyzed by high-resolution synchrotron X-ray powder diffraction. Remarkable broadening of diffraction peaks in samples annealed at temperatures above 200,°C is observed (see figure), indicating heat-induced degradation of intra-crystalline proteins occluded in the mineral lattice during biomineralization. [source] Outcomes of the International Union of Crystallography Commission on Powder Diffraction Round Robin on Quantitative Phase Analysis: samples 2, 3, 4, synthetic bauxite, natural granodiorite and pharmaceuticalsJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 4 2002Nicola V. Y. Scarlett The International Union of Crystallography (IUCr) Commission on Powder Diffraction (CPD) has sponsored a round robin on the determination of quantitative phase abundance from diffraction data. The aims of the round robin have been detailed by Madsen et al. [J. Appl. Cryst. (2001), 34, 409,426]. In summary, they were (i) to document the methods and strategies commonly employed in quantitative phases analysis (QPA), especially those involving powder diffraction, (ii) to assess levels of accuracy, precision and lower limits of detection, (iii) to identify specific problem areas and develop practical solutions, (iv) to formulate recommended procedures for QPA using diffraction data, and (v) to create a standard set of samples for future reference. The first paper (Madsen et al., 2001) covered the results of sample 1 (a simple three-phase mixture of corundum, fluorite and zincite). The remaining samples used in the round robin covered a wide range of analytical complexity, and presented a series of different problems to the analysts. These problems included preferred orientation (sample 2), the analysis of amorphous content (sample 3), microabsorption (sample 4), complex synthetic and natural mineral suites, along with pharmaceutical mixtures with and without an amorphous component. This paper forms the second part of the round-robin study and reports the results of samples 2 (corundum, fluorite, zincite, brucite), 3 (corundum, fluorite, zincite, silica flour) and 4 (corundum, magnetite, zircon), synthetic bauxite, natural granodiorite and the synthetic pharmaceutical mixtures (mannitol, nizatidine, valine, sucrose, starch). The outcomes of this second part of the round robin support the findings of the initial study. The presence of increased analytical problems within these samples has only served to exacerbate the difficulties experienced by many operators with the sample 1 suite. The major difficulties are caused by lack of operator expertise, which becomes more apparent with these more complex samples. Some of these samples also introduced the requirement for skill and judgement in sample preparation techniques. This second part of the round robin concluded that the greatest physical obstacle to accurate QPA for X-ray based methods is the presence of absorption contrast between phases (microabsorption), which may prove to be insurmountable in some circumstances. [source] Outcomes of the International Union of Crystallography Commission on Powder Diffraction Round Robin on Quantitative Phase Analysis: samples 1a to 1hJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 4 2001Ian C. Madsen The International Union of Crystallography (IUCr) Commission on Powder Diffraction (CPD) has sponsored a round robin on the determination of quantitative phase abundance from diffraction data. Specifically, the aims of the round robin were (i) to document the methods and strategies commonly employed in quantitative phase analysis (QPA), especially those involving powder diffraction, (ii) to assess levels of accuracy, precision and lower limits of detection, (iii) to identify specific problem areas and develop practical solutions, (iv) to formulate recommended procedures for QPA using diffraction data, and (v) to create a standard set of samples for future reference. Some of the analytical issues which have been addressed include (a) the type of analysis (integrated intensities or full-profile, Rietveld or full-profile, database of observed patterns) and (b) the type of instrument used, including geometry and radiation (X-ray, neutron or synchrotron). While the samples used in the round robin covered a wide range of analytical complexity, this paper reports the results for only the sample 1 mixtures. Sample 1 is a simple three-phase system prepared with eight different compositions covering a wide range of abundance for each phase. The component phases were chosen to minimize sample-related problems, such as the degree of crystallinity, preferred orientation and microabsorption. However, these were still issues that needed to be addressed by the analysts. The results returned indicate a great deal of variation in the ability of the participating laboratories to perform QPA of this simple three-component system. These differences result from such problems as (i) use of unsuitable reference intensity ratios, (ii) errors in whole-pattern refinement software operation and in interpretation of results, (iii) operator errors in the use of the Rietveld method, often arising from a lack of crystallographic understanding, and (iv) application of excessive microabsorption correction. Another major area for concern is the calculation of errors in phase abundance determination, with wide variations in reported values between participants. Few details of methodology used to derive these errors were supplied and many participants provided no measure of error at all. [source] Tricalcium Silicate T1 and T2 Polymorphic Investigations: Rietveld Refinement at Various Temperatures Using Synchrotron Powder DiffractionJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2004Vanessa K. Peterson The lattice parameters, cell volume, and structure of a sample of phase pure triclinic tricalcium silicate were determined using in situ, high-temperature synchrotron powder diffraction and full-profile Rietveld refinement. The temperature range covered was from ambient to 740°C. Evidence of superstructure was found. The T2 type structure with disordered SiO4 tetrahedra was observed, and an average structure for the subcell (P, a= 11.7416(2) Å, b= 14.2785(2) Å, c= 13.7732(2) Å, ,= 105.129(1)°, ,= 94.415(1)°, and ,= 89.889(1)°) is presented. Differential thermal analysis and X-ray fluorescence was also performed. [source] Hydrolysis of Pure and Sodium Substituted Calcium Aluminates and Cement Clinker Components Investigated by in Situ Synchrotron X-ray Powder DiffractionJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2004Axel Nørlund Christensen The hydrolysis of pure and sodium-substituted calcium aluminates and cement clinker phases was investigated in situ in the temperature range 25°,170°C, using the angle dispersive powder synchrotron powder X-ray diffraction technique. The final hydrolysis product in all cases was Ca3Al2(OH)12. The intermediate phase Ca4Al2O7·19H2O was formed from the pure calcium aluminates, and the intermediate phases Ca4Al2O7·xH2O, x= 11, 13, or 19, were formed from the cement clinker phases. [source] Observation and Characterization of Structural Phase Transitions by X-Ray Powder DiffractionPARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 6 2005Wulf Depmeier Abstract Some of the basic properties of powder diffraction are summarized after a short introduction into the theory. Then it is described phenomenologically how various kinds of structural transformations affect the powder diffraction pattern. This is achieved on emphasizing that diffraction studies on powders are statistically more sound than those on single crystals, thus allowing the reliable determination of the generic properties of a given crystal structure. [source] Characterization of an Area Polluted by Copper and Zinc: the Relation between Soil Texture, Mineralogy and Pollutant ConcentrationACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 6 2009Caterina RINAUDO Abstract: Twenty-four soil samples were collected at three depths from an approximately 2.5 acre contaminated site in southern Piedmont (Italy) and then analyzed. The main soil parameters determined were: pH, Cation Exchange Capacity (CEC), particle size distribution, total organic carbon (TOC) content and retained metal concentration. The mineral phases were identified by X-Ray Powder Diffraction (XRPD). All of the samples contained Zn and Cu resulting from industrial contamination during the last century, and those obtained at depths of 20,40 cm consistently showed the highest levels. To determine which size fraction was most active in the retention process, the samples were separated into four fractions (,2 mm, ,63 ,m, ,30 ,m and ,2 ,m) and the amount of pollutant measured in each. It was found that metal retention was the highest in the clayey fraction, whose clay minerals were identified by XRPD after K+ and Mg2+ saturation, glycerol treatment and heating to 550° C. The clayey fraction was also the richest in TOC, and a direct correlation between TOC amount and metal retention was observed. [source] ChemInform Abstract: Study of the Crystal Chemistry of the n = 2 Ruddlesden,Popper Phases Sr3FeMO6+, (M: Fe, Co, and Ni) Using in situ High Temperature Neutron Powder Diffraction.CHEMINFORM, Issue 40 2009Liliana V. Mogni Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: La(Ni2/3Nb1/3)O3 by Neutron Powder Diffraction.CHEMINFORM, Issue 30 2009Julian R. Tolchard Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] High-Temperature Processing of Ba3ZnTa2O9: An in situ Study Using Synchrotron X-Ray Powder Diffraction.CHEMINFORM, Issue 48 2007Phillip M. Mallinson Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Crystal Structure and Site Preference of Ba-Doped ,-Tricalcium Phosphate (Ca1-xBax)3(PO4)2 Through High-Resolution Synchrotron Powder Diffraction (x = 0.05 to 0.15).CHEMINFORM, Issue 42 2007Masatomo Yashima Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Phase Transitions in [Ca(H2O)4](NO3)2 Studied by Differential Scanning Calorimetry, X-Ray Single Crystal Diffraction and Neutron Powder Diffraction.CHEMINFORM, Issue 25 2007Part 1. Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] In situ X-Ray Powder Diffraction, Synthesis, and Magnetic Properties of InVO3.CHEMINFORM, Issue 9 2007Rylan J. Lundgren Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Synthesis and Crystal Structure Determination by X-Ray Powder Diffraction of Nickel Tetrametaphosphimate Octahydrate Ni2(PO2NH)4×8H2O.CHEMINFORM, Issue 43 2005S. Rebecca Roemer Abstract For Abstract see ChemInform Abstract in Full Text. [source] Thallium Selenate (Tl2SeO4) in a Paraelastic Phase by X-Ray Powder Diffraction.CHEMINFORM, Issue 27 2005Yasumitsu Matsuo Abstract For Abstract see ChemInform Abstract in Full Text. [source] Characterization of Beryllium Selenates by X-Ray Powder Diffraction, DTA and DSC.CHEMINFORM, Issue 1 2005V. G. Koleva Abstract For Abstract see ChemInform Abstract in Full Text. [source] Characterization of La2NiO4+, Using in situ High Temperature Neutron Powder Diffraction.CHEMINFORM, Issue 32 2003Stephen J. Skinner Abstract For Abstract see ChemInform Abstract in Full Text. [source] X-Ray Powder Diffraction and 57Fe Moessbauer Spectroscopy Study on Fe0.47NbS2.CHEMINFORM, Issue 12 2003L. Ehm Abstract For Abstract see ChemInform Abstract in Full Text. [source] Evidence of Ni(III) Disproportionation in the TlNiO3 Perovskite Lattice Through Neutron Powder Diffraction and Moessbauer Spectroscopy.CHEMINFORM, Issue 10 2003S. J. Kim Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthetic Hydrocerussite, 2PbCO3×Pb(OH)2, by X-Ray Powder Diffraction.CHEMINFORM, Issue 38 2002Pauline Martinetto Abstract For Abstract see ChemInform Abstract in Full Text. [source] The First Crystal Structures of Industrial Laked Yellow Pigments Determined by X-ray Powder DiffractionCHEMISTRY - A EUROPEAN JOURNAL, Issue 2 2009Martin For more than 100 years, laked azo pigments (i.e., dyestuff anions combined with M2+ cations) have been industrially produced, but crystal structures of commercial laked pigments have never been reported. The crystal structures of two such pigments were determined from laboratory X-ray powder data (see graphic). [source] Low temperature powder diffraction and DFT solid state computational study of hydrogen bonding in NH4VO3CRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2009. Smr Abstract The crystal structure of NH4VO3 was refined by the geometry optimization done by total energy minimization in solid state using DFT/plane waves approach. The lattice parameters were derived by the Le Bail technique from the low temperature X-ray (40-293 K) and synchrotron (100-293 K) powder diffraction data. The structure is formed by the infinite chains of irregular VO4 tetrahedra running approximately parallel to the c -axis, which are interlinked by the ammonium ions placed between them. The ammonium ions link to the [VO4], chains through one linear, one bifurcated and two trifurcated N-H,O hydrogen bonds. Considering their stability there are six distinct N-H,O hydrogen bonds: two strong with the N-H,O bond angles close to the straight, two medium with the bond angles of 123° and 148° and two very bent (105° and 107°) and hence weak hydrogen bonds. There is a reasonable agreement between the energies of the stretching ,(NH) modes estimated using the optimised N,O contact distances and those obtained experimentally. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Low temperature hydrothermal growth and optical properties of ZnO nanorodsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2009J. H. Yang Abstract Well-faceted hexagonal ZnO nanorods have been synthesized by a simple hydrothermal method at relative low temperature (90°C) without any catalysts or templates. Zinc oxide (ZnO) nanorods were grown in an aqueous solution that contained Zinc chloride (ZnCl2, Aldrich, purity 98%) and ammonia (25%). Most of the ZnO nanorods show the perfect hexagonal cross section and well-faceted top and side surfaces. The diameter of ZnO nanorods decreased with the reaction time prolonging. The samples have been characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) measurement. XRD pattern confirmed that the as-prepared ZnO was the single-phase wurtzite structure formation. SEM results showed that the samples were rod textures. The surface-related optical properties have been investigated by photoluminescence (PL) spectrum and Raman spectrum. Photoluminescence measurements showed each spectrum consists of a weak band ultraviolet (UV) band and a relatively broad visible light emission peak for the samples grown at different time. It has been found that the green emission in Raman measurement may be related to surface states. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Crystal structure refinement of the ternary compound Cu2SnTe3 by X-ray powder diffractionCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2008G. E. Delgado Abstract The ternary compound Cu2SnTe3 crystallizes in the Imm2 (Nº 44) space group, Z = 2, with a = 12.833(4) Å, b = 4.274(1) Å, c = 6.043(1) Å, V = 331.5(1) Å3. Its structure was refined from X-ray powder diffraction data using the Rietveld method. The refinement of 25 instrumental and structural variables led to Rp = 10.2%, Rwp = 11.8%, Rexp = 7.7%, RB = 10.6%, S = 1.6 and ,2 = 2.6, for 5501 step intensities and 163 independent reflections. This compound is isostructural with Cu2GeSe3, and consists of a three-dimensional arrangement of slightly distorted CuTe4 and SnTe4 tetrahedra connected by common corners. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Crystal growth, optical and luminescence properties of (Ce,Sr)-doped PrAlO3 single crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2007A. Novoselov Abstract Using the micro-pulling-down method, (Ce,Sr)-doped PrAlO3 square-shaped single crystals (4×4×12 mm) were grown. Structural parameters studied by X-ray powder diffraction were consistent with R3m space group. Compositional homogeneity was checked with electron probe micro-analysis and found quite uniform. Absorption spectra and luminescence characteristics under UV and X-ray excitations were measured at room temperature with no Ce-related emission appeared. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Solvothermal growth of single-crystal hexagonal prismatic SrCO3 microrodsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2007Fanglin Du Abstract Single-crystal hexagonal prism SrCO3 microrods have been prepared by a simple solvothermal route. The effects of the reaction time, the content of 1,2-propanediol and the reactants mass on the products have been investigated, respectively. The as-synthesized microrods were characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The results reveal that the products have uniform shape and excellent monodispersity. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth and photorefractive properties of Mg:Ce:Cu:LiNbO3 crystals grown by Czochralski methodCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2006Y. X. Fan Abstract In this paper, photorefractive properties of Mg:Ce:Cu:LiNbO3 crystals were studied. The crystals doped with different concentration of Mg ions have been grown by the Czochralski method. Mg concentrations in grown crystals were analyzed by an inductively coupled plasma optical emission spectrometry (ICP-OE/MS). The crystal structures were analyzed by the X-ray powder diffraction (XRD), ultraviolet-visible (UV-Vis) absorption spectra and infrared (IR) transmitatance spectra. The photorefractive properties of crystals were experimentally studied by using two-beam coupling. In this experiment we determined the writing time, maximum diffraction efficiency and the erasure time of crystals samples with He-Ne laser. The results showed that the dynamic range (M/#), sensitivity (S) and diffraction efficiency (,) were dependent on the Mg doping concentration, and the Mg(4.58mol%):Ce:Cu:LiNbO3 crystal was the most proper holographic recording media material among the six crystals studied in the paper. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Crystal structure and thermal behaviour of (Rb,Cs)BSi2O6 solid solutionsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2006M. G. Krzhizhanovskaya Abstract The crystal chemistry of Rb-Cs boroleucites has been studied by means of X-ray powder diffraction at room and elevated temperatures. The cubic I-43d , cubic Ia3d phase transition was investigated using a series of samples prepared by solid-state reaction along the pseudobinary system RbBSi2O6 - CsBSi2O6. The Rietveld refinement of the structures of Rb1-xCsxBSi2O6 solid solutions (x = 0.2, 0.4, 0.6, 0.8) demonstrates that the solutions with a high Rb content crystallise in the cubic I-43d space group, and the boroleucites with a considerable Cs content have Ia3d symmetry. Rb can substitute Cs in a wide range of compositions. Within a narrow range of x = 0.5 - 0.6 immiscibility was revealed. Under Rb-Cs substitution the cubic lattice parameter, the (Rb,Cs)-O distances, and the angles between tetrahedra of the I-43d phase change clearly, while those of the Ia3d phase change slightly. The HTXRD data shows that the I-43d phase transforms into a Ia3d phase on heating analogously to a change of the composition. As the Cs content increases the transition temperature decreases. The low temperature I-43d phase shows a higher thermal expansion than the high temperature Ia3d phase. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim [source] | |||||||||||||||||||||||||||||||||||||