Some calculations for powder patterns

Visser, J. W. M.

doi:10.1107/s0021889869006741

Cited by 66 publications

(78 citation statements)

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“…50, 0.7 mm diameter) and sealed. Indexing with ITO (Visser, 1969) led to a body-centred monoclinic cell which could be transformed to a rhombohedral cell. X-rays of wavelength 0.84979 (1) A Ê were selected by a double Si(311) sagitally focusing monochromator.…”

Section: Methodsmentioning

confidence: 99%

Disorder determined by high-resolution powder diffraction: structure of pentamethylcyclopentadienyllithium

Dinnebiér

Schneider

Smaalen³

et al. 1999

Acta Crystallogr Sect B

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The crystal structure of pentamethylcyclopentadienyllithium, [Li(C(10)H(15))] (LiCp*), has been determined from a high-resolution powder pattern by modelling and the maximum entropy method (MEM). The compound crystallizes in space group R3m with lattice parameters a = b = 14.7711 (5), c = 3.82206 (6) Å and V = 722.19 (4) Å(3) (Z = 3). LiCp* forms polymeric 'multidecker' chains along the c axis. The pentamethylcyclopentadienyl anions are coplanar with each other and show threefold rotational disorder. The MEM calculations did not only confirm the structural model and the type of disorder, but also discovered additional symmetry compared with the Rietveld analysis. This is the first solid-state structure of a Lewis-base-free alkali metal Cp* compound.

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Section: Methodsmentioning

confidence: 99%

Disorder determined by high-resolution powder diffraction: structure of pentamethylcyclopentadienyllithium

Dinnebiér

Schneider

Smaalen³

et al. 1999

Acta Crystallogr Sect B

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“…31 Only the ITO indexing program 32 consistent with a molecule of this size (2 molecules in the unit cell assuming 18 Å 3 for each non-H atom). Therefore the obtained peak positions were used as the basis of indexing attempt using the range of indexing programs available in the CMPR program.…”

Section: Characterisation Of Polymorphic Formsmentioning

confidence: 99%

Investigation into solid and solution properties of quinizarin

et al. 2015

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Polymorphism, crystal shape and solubility of 1,4-dihydroxyanthraquinone (quinizarin) have been investigated in acetic acid, acetone, acetonitrile, n-butanol and toluene. The solubility of FI and FII from 20 degrees C to 45 degrees C has been determined by a gravimetric method. By slow evaporation, pure FI was obtained from n-butanol and toluene, pure FII was obtained from acetone, while either a mixture of the two forms or pure FI was obtained from acetic acid and acetonitrile. Slurry conversion experiments have established an enantiotropic relationship between the two polymorphs and that the commercially available FI is actually a metastable polymorph of quinizarin under ambient conditions. However, in the absence of FII, FI is kinetically stable for many days over the temperature range and in the solvents investigated. FI and FII have been characterized by infrared spectroscopy (IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), transmission and ordinary powder X-ray diffraction (PXRD) at different temperatures. The crystal structure of FII has been determined by single-crystal XRD. DSC and high-temperature PXRD have shown that both FI and FII will transform into a not previously reported hightemperature form (FIII) around 185 degrees C before this form melts at 200-202 degrees C. By indexing FIII PXRD data, a triclinic P (1) over bar cell was assigned to FIII. The solubility of quinizarin FI and FII in the pure organic solvents used in the present work is below 2.5% by weight and decreases in the order: toluene, acetone, acetic acid, acetonitrile and n-butanol. The crystal shapes obtained in different solvents range from thin rods to flat plates or very flat leaves, with no clear principal difference observed between FI and FII.

QC 20160226

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“…A high resolution X-Ray powder diffraction pattern was thus recorded at the Swiss Norwegian Beamline at ESRF. The pattern of MIL-131 was indexed with the Dicvolgv program [17]. Solutions with adequate figures of merit were found (M(25) = 75/425 (0.0014, 41)).…”

Section: Structure Determinationmentioning

confidence: 99%

Synthesis, structure and solid state NMR analysis of a new templated titanium(III/IV) fluorophosphate

Serre

Haouas

Taulèlle

et al. 2010

Comptes Rendus. Chimie

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Some calculations for powder patterns

Abstract: The elements of the unit cell are expressed in the coefficients A⋯F of the quadratic form 1/d2 = Q(h,k,l), and a table of derivatives δa/δA⋯δ cos γ/δF is given. The elements of Delaunay's foursider are calculated in a simple way from A⋯F.

Cited by 66 publications

References 0 publications

Disorder determined by high-resolution powder diffraction: structure of pentamethylcyclopentadienyllithium

Disorder determined by high-resolution powder diffraction: structure of pentamethylcyclopentadienyllithium

Investigation into solid and solution properties of quinizarin

Synthesis, structure and solid state NMR analysis of a new templated titanium(III/IV) fluorophosphate

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