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High-Resolution Synchrotron Powder Diffraction (high-resolution + synchrotron_powder_diffraction)
Selected AbstractsThe 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] 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] Performance of a new furnace for high-resolution synchrotron powder diffraction up to 1900,K: application to determine electron density distribution of the cubic CaTiO3 perovskite at 1674,KJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 5 2004Masatomo Yashima Accurate crystal structure analysis at high temperatures is an important challenge in science and technology. A new electric furnace for the measurement of high-resolution (,d/d = 0.03%) synchrotron radiation powder diffraction profiles from materials at high temperatures (up to 1900,K in air) has been designed and fabricated. This furnace consists of a ceramic refractory with MoSi2 heaters, an aluminium body cooled by flowing water, and a sample stage with a spinner and a controller for sample-height adjustment. In situ synchrotron powder diffraction measurement for a calcium titanate perovskite specimen at 1674,K has been performed using the furnace at beamline 3A of the Photon Factory. The electron density distribution of the cubic perovskite at 1674,K was successfully obtained using a combination of Rietveld refinement, the maximum-entropy method (MEM) and MEM-based pattern-fitting techniques. The Ti atoms exhibit covalent bonding with the O atoms in the cubic CaTiO3 perovskite at this temperature, while the Ca atoms are ionic. These results indicate that the new furnace yields high-quality data for accurate crystal structure analysis. [source] Instrument line-profile synthesis in high-resolution synchrotron powder diffractionJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2003O. Masson An accurate method for synthesizing the instrumental line profile of high-resolution synchrotron powder diffraction instruments is presented. It is shown that the instrumental profile can be modelled by the convolution of four physical aberration functions: the equatorial intensity distribution, the monochromator and analyser transfer functions, and the axial divergence aberration function. Moreover, each equatorial aberration is related to an angle-independent function by a scale transform factor. The principles of the instrument line-profile calculation are general. They are applied in the case of the angle-dispersive powder X-ray diffraction beamline BM16 at the ESRF. The effects of each optical element on the overall instrument profile are discussed and the importance of the quality of the different optical elements of the instrument is emphasized. Finally, it is shown that the high resolution combined with the precise modelling of the instrument profile shape give access to a particle size as large as 3,µm. [source] | ||||||||||