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Energy-dispersive X-ray Diffraction (energy-dispersive + x-ray_diffraction)
Selected AbstractsIn-situ Energy-Dispersive X-ray Diffraction Studies of Crystal Growth and Compound Conversion Under Solvothermal ConditionsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2003Lars Engelke Abstract The results of in-situ energy-dispersive X-ray diffraction under solvothermal conditions performed on isostructural, layered thioantimonates Mn2Sb2S5·L (L = amine) demonstrate the great potential of the method. When the synthesis was carried out at low temperatures with L being 1,3-diaminopropane (DAP), two crystalline intermediate phases were detected which then grew and disappeared when product growth started. Surprisingly, when N -methyl-1,3-diaminopropane (MDAP) was used, no crystalline intermediates could be detected and the induction time was significantly shorter than for DAP. For reactions up to 100 °C and for higher temperatures with , < 0.8 (, is the extent of reaction), the crystallisation is predominantly controlled by nucleation. Further progress of crystallisation (, > 0.8) leads to a change of the dominant process and a diffusion-controlled mechanism is observed. During the reaction with diethylenetriamine (DIEN), three crystalline intermediates were detected prior to product growth. The induction time is longer than for the other two compounds. The crystallisation seems to be diffusion-controlled and is faster than for the DAP and MDAP compounds. In a solution of DIEN, the crystalline phases Mn2Sb2S5·L (L = DAP or MDAP) are transformed into the DIEN product under solvothermal conditions, and a rigorous analysis of the intensities of the reflections suggests a partial dissolution of the crystalline starting materials followed by crystallisation of the DIEN material. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Anomalous Dynamical Charge Change Behavior of Nanocrystalline 3C-SiC upon CompressionJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2004Haozhe Liu Using diamond anvil cell (DAC) technique, in situ high-pressure Raman scattering and energy-dispersive X-ray diffraction (EDXRD) experiments were used at room temperature to study 3C-SiC with an average grain size of 30 nm. In contrast to its bulk counterpart, a decrease of the Born's transverse effective charge of these nanocrystals was observed with increasing pressure from measurements of the longitudinal and transverse optical phonon modes (longitudinal optical,transverse optical) splitting. This is therefore indicative of a diminishing ionicity of nanocrystalline 3C-SiC on compression. [source] Reactive magnetron sputtering of highly (001)-textured WS2,x films: Influence of Ne+, Ar+ and Xe+ ion bombardment on the film growthPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2006K. Ellmer Abstract Layer-type van der Waals semiconductor WS2,x films were grown by radio frequency reactive magnetron sputtering from a metallic tungsten target onto oxidized silicon substrates. The sputtering atmosphere consisted of 75% hydrogen sulfide and 25% neon, argon or xenon. The substrate voltage and hence the energy of the ions bombarding the growing film, was varied from about 20 V (floating potential) to ,80 V. By in situ energy-dispersive X-ray diffraction the growth of the films was monitored and by elastic recoil detection analysis the film composition was measured. It was found that with xenon in the sputtering atmosphere a substrate voltage of ,20 V is sufficient to suppress the crystalline film growth, while for argon as the sputtering rare gas this occurs only at ,80 V. The disturbed film growth is accompanied by a sulfur loss of the growing WS2,x films down to x = 1.1 for sputtering in Ar + H2S at a substrate potential of ,60 V. The results are tentatively explained by the different momentum transfers to sulfur atoms, which is highest for argon ions. It has also to be taken into account that the low-energy xenon bombardment is a many-body cascade process with a much higher local energy density compared to argon and neon bombardment and leading to a higher defect density and a supression of the crystalline growth. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Substitutional and positional disorder in Sr2.88Cu3.12(PO4)4ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2010Ljiljana Karanovi The title compound, a hydrothermally synthesized strontium copper(II) phosphate(V) (2.88/3.12/4), is isotypic with Sr3Cu3(PO4)4, obtained previously by solid-state reaction, but not with Sr3Cu3(PO4)4, obtained previously by the hydrothermal method. A surplus of copper was observed by both structural and chemical analysis, and the formula obtained by the structural analysis is in full agreement with results of the EDX (energy-dispersive X-ray diffraction) analysis. The structure consists of layers of Cu3O12 groups which are linked via the PO4 tetrahedra. The Cu3O12 groups are formed by one Cu1O4 and two Cu2O5 coordination polyhedra sharing corners. The central Cu1 atom of the Cu3O12 group is located at an inversion centre (special position 2a). The unique structural feature of the title compound is the presence of 12% Cu in the Sr1 site (special position 2b, site symmetry ). Moreover, disordered Sr2 atoms were observed: a main site (Sr2a, 90%) and a less occupied site (Sr2b, 10%) are displaced by 0.48,(3),Å along the b axis. Such substitutional and positional disorder was not observed previously in similar compounds. [source] Tuning the Magnetic Properties of LixCrTi0.25Se2 (0.03,x,0.7) by Directed Deintercalation of LithiumCHEMISTRY - A EUROPEAN JOURNAL, Issue 16 2008Malte Behrens Dr. Abstract X-ray diffraction (XRD), in situ energy-dispersive X-ray diffraction (EDXRD), X-ray absorption near-edge structure (XANES), extended X-ray absorption fine structure (EXAFS), and magnetic measurements were applied to investigate the effects of lithium deintercalation on pseudolayered Li0.70CrTi0.25Se2. A detailed picture of structural changes during the deintercalation process was obtained by combining the results of EDXRD and EXAFS. Removal of Li from the host,guest complex leads to anisotropic contraction of the unit cell with stronger impact on the c axis, which is the stacking axis of the layers. The EDXRD experiments evidence that the shrinkage of the lattice parameters with decreasing xLi in LixCrTi0.25Se2 is nonlinear in the beginning and then becomes linear. Analysis of the EXAFS spectra clearly shows that the Cr/TiSe distances are affected in a different manner by Li removal. The CrSe bond lengths decrease, whereas the TiSe bonds lengthen when the Li content is reduced, which is consistent with XRD data. Magnetic measurements reveal a change from predominantly antiferromagnetic exchange (,p=,300,K) interactions for the pristine material to ferromagnetic exchange interactions (,=25,K) for the fully intercalated material. Thus, the magnetic properties can be altered under ambient conditions by directed adjustment of the dominant magnetic exchange. The unusual magnetic behavior can be explained on the basis of the variation of the metal,metal distances and the Cr-Se-Cr angles with x, which were determined by Rietveld refinements. Owing to competing ferromagnetic and antiferromagnetic exchange interactions and disorder, the magnetic ground state of the intercalated materials is characterized by spin-glass or spin-glass-like behavior. [source] | ||||||||||