Powder diffraction studies

X-ray powder diffraction studies are perfonned both with films and with counter diffractometers. The powder photograph was developed by P Debye and P Scherrer and, independently, by A W Hull. The Debye-Scherrer camera has a cylindrical specimen surrounded by a cylindrical film. In another commonly used powder... 

Powder diffraction studies with neutrons are perfonned both at nuclear reactors and at spallation sources. In both cases a cylindrical sample is observed by multiple detectors or, in some cases, by a curved, position-sensitive detector. In a powder diffractometer at a reactor, collimators and detectors at many different 20 angles are scaimed over small angular ranges to fill in the pattern. At a spallation source, pulses of neutrons of different wavelengdis strike the sample at different times and detectors at different angles see the entire powder pattern, also at different times. These slightly displaced patterns are then time focused , either by electronic hardware or by software in the subsequent data analysis. 

In addition, an interesting, although negative, result has come from powder diffraction studies of the hexachloro compounds. We have examined Debye—Scherrer photographs of several samples known to contain predominantly hexachlorodibenzo-p-dioxins and have identified the patterns of at least three crystalline phases therein. (There are 10 possible isomers of hexachlorodibenzo-p-dioxin.) These patterns have been checked carefully against the calculated d-spacings and intensities of the 1,2,3,7,8,9-hexa isomer described by Cantrell, Webb, and Mabis (I) and also against an observed pattern supplied by Cantrell and believed to be from the low temperature phase of the same material. Yet to date we... 

The Ir complex (NH4)[Ir(NH3)Cl5] has been prepared by the oxidation of the Ir111 analogue with Cl2 at 330 °C, and its structure determined from powder diffraction studies.30... 

Mohammad Jafar Soltanian Fard-Jahromi and Ali Morsali (2010) Sonochemical synthesis of nanoscale mixed-ligands lead(II) coordination polymers as precursors for preparation of Pb2(S04)0 and PbO nanoparticles thermal, structural and X-ray powder diffraction studies. Ultrason Sonochem 17(2) 435-440... 

A room temperature powder X-ray diffraction pattern for Na8[GaSi04]6(C104)2 Sodalite with Si as an internal standard for phase identification in the reaction products has been studied. X-ray powder diffraction study confirms the cubic structure of Na8[GaSi04]6(C104)2 sodalite synthesized... 

Cheetham, N. W.H. and Tao, L. (1998). Variation in crystalline type with amylose content in maize starch granules X-ray powder diffraction study. Carbohydrate Polymers. 36, 277-284. 

G. (2005) Very large swelling in hydrid frameworks a combined computational and powder diffraction study. J. Am. Chem. Soc., 127, 15273-15278. 

Earlier X-ray powder diffraction studies by de Haan and Visser provided similar results. These authors investigated the impact of the selenium content on the structure type of the crystals and deduced the existence of eight-memteed ring molecules but were unable to decide whether the crystals consisted of binary compounds of sulfur and selenium or simply of Seg and Sg. 

While the stoichiometric salt formations with HX are clear-cut if the acid cannot be removed simply by evacuation, there may be questions of salt formation versus complexation in solid-solid reactions between acids and bases. This point has been suitably addressed with IR spectroscopy and X-ray powder diffraction studies of solid carboxylic acids and amine bases of varying strengths that were ground or milled together [34]. Yields are not given, but it may be assumed that quantitative reactions occurred in all stoichiometric mixtures. 

At the same time the structures in the solid state of Mc2Mg and Et2Mg were determined by X-ray powder diffraction studies . Both compounds form polymeric chains as the result of the bridging of two methyl groups between two magnesium atoms, rendering the magnesium atoms almost perfectly tetrahedrally coordinated. 

Despite their extensive synthetic use, it is only quite recently that the NLi species have been isolated and examined. The first singlecrystal structure of a lithium amide was the [(Me3Si)2NLi]3 trimer. This structure was fully described in 1978 (17) [although a powder diffraction study in 1969 also indicated a trimer to be present (18)]. Some synthetic advantages of isolating crystalline lithium amides... 

The minimal structure demand for the OMe-group is leading to the maximal coordination of the metal atoms resulting in the fact that the majority of methoxides — both crystalline and amorphous — are polymeric. The powder diffraction studies have shown that many methoxides (and sometimes ethox-... 

Acetylides (continued) liquid crystals, 12, 246 powder diffraction studies, 1, 586 in Ru—Os mixed-metals, 6, 1081 j2-Acetylides, in triruthenium and triosmium clusters, 6, 761... 

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