Integration of single-crystal reflections using area multidetectors

Wilkinson, C.; Khamis, H. W.; Stansfield, Robert F. D.; McIntyre, G. J.

doi:10.1107/s0021889888005400

Cited by 226 publications

(202 citation statements)

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“…A twodimensional 80 × 80 mm 2 area detector was used for all measurements [28]. An asymmetric cryomagnet with vertical opening of +20 • and −5 • supplying a magnetic field of up to 60 kOe was used throughout the experiment.…”

Section: Methodsmentioning

confidence: 99%

Field-induced magnetic states in holmium tetraboride

et al. 2017

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A study of the zero field and field induced magnetic states of the frustrated rare earth tetraboride HoB 4 has been carried out using single crystal neutron diffraction complemented by magnetization measurements. In zero field, HoB 4 shows magnetic phase transitions at T N1 = 7.1 K to an incommensurate state with a propagation vector (δ,δ,δ ), where δ = 0.02 and δ = 0.43 and at T N2 = 5.7 K to a noncollinear commensurate antiferromagnetic structure. Polarized neutron diffraction measurements in zero field have revealed that the incommensurate reflections, albeit much reduced in intensity, persist down to 1.5 K despite antiferromagnetic ordering at 5.7 K. At lower temperatures, application of a magnetic field along the c axis initially re-establishes the incommensurate phase as the dominant magnetic state in a narrow field range, just prior to HoB 4 ordering with an up-up-down ferrimagnetic structure characterized by the (h k 1 3 )-type reflections between 18 and 24 kOe. This field range is marked by the previously reported M/M sat = 1 3 magnetization plateau, which we also see in our magnetization measurements. The region between 21 and 33 kOe is characterized by the increase in the intensity of the antiferromagnetic reflections, such as (100), the maximum of which coincides with the appearance of the narrow magnetization plateau with M/M sat ≈ 3 5 . Further increase of the magnetic field results in the stabilization of a polarized state above 33 kOe, while the incommensurate reflections are clearly present in all fields up to 59 kOe. We propose the H -T phase diagram of HoB 4 for the H c containing both stationary and transitionary magnetic phases which overlap and show significant history dependence.

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Section: Methodsmentioning

confidence: 99%

Field-induced magnetic states in holmium tetraboride

et al. 2017

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“…The crystal was rotated 20° between patterns, which were recorded in exposures of 90 minutes. The patterns were indexed using the program LAUEGEN 63,64 and the reflections integrated using the local program INTEGRATE+ 65 and normalised to a common incident wavelength using the program rearrange. Correction for absorption was deemed unnecessary in view of the small sample volume.…”

Section: Neutron Single-crystal Diffractionmentioning

confidence: 99%

New Insights into an Old Molecule: Interaction Energies of Theophylline Crystal Forms

Fucke

McIntyre

Wilkinson

et al. 2012

Crystal Growth & Design

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'New insights into an old molecule : interaction energies of theophylline crystal forms.', Crystal growth design., 12 (3). pp. 1395-1401. Further information on publisher's website:http://dx.doi.org/10.1021/cg201499sPublisher's copyright statement:This document is the Accepted Manuscript version of a Published Work that appeared in nal form in Crystal growth design, copyright c American Chemical Society after peer review and technical editing by the publisher. To access the nal edited and published work see http://dx.doi.org/10.1021/cg201499sAdditional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO• the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. The asthma therapeutic theophylline exists in at least three anhydrous polymorphs and a monohydrate. The single-crystal X-ray structure of the high-temperature polymorph form I is presented for the first time and the energetic relationship between forms I and II is investigated using the partial charges and chemical hardness analysis (PACHA) algorithm. It is shown that the interactions in the form I crystal network are stronger, especially the hydrogen bond. The singlecrystal neutron structure of the monohydrate demonstrates static disorder of the water molecule as well as dynamic disorder of the methyl groups. PACHA investigations based on the neutron coordinates reveal that the homomeric interactions in this form are stronger than the interaction of the water with the host molecules. The dehydration of the hydrate should thus leave the theophylline network intact, explaining the isomorphic powder X-ray diffractograms of the monohydrate and its dehydrated form III.

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“…The cell dimensions were refined using the ILL program RAFD9 and integrated intensities produced using the ILL program RACER. 35 The data were corrected for absorption in the crystal using the program DATAP. 36 Crystal structure refinements of the reduced squared structure factors (F 2 ) were performed using the program FULLPROF.…”

Section: Single Crystal Structure At 16 K From Neutron Diffractionmentioning

confidence: 99%

On the Nature of the Spin Frustration in the CuO₂ Ribbon Chains of LiCuVO₄: Crystal Structure Determination at 1.6 K, Magnetic Susceptibility Analysis, and Density Functional Evaluation of the Spin Exchange Constants

et al. 2011

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The spin-1/2 Cu 2+ ions of LiCuVO 4 form one-dimensional chains along the bdirection, and the spin frustration in LiCuVO 4 is described in terms of the nearestneighbor ferromagnetic exchange J 1 and the next-nearest-neighbor antiferromagnetic exchange J 2 in these chains. Recently, it has become controversial whether or not J 1 is stronger in magnitude than J 2 . To resolve this controversy, we determined the crystal structure of LiCuVO 4 at 1.6 K by neutron diffraction, analyzed the magnetic susceptibility of LiCuVO 4 to deduce the Curie-Weiss temperature  and the J 2 /J 1 ratio, and finally extracted the spin exchange constants of LiCuVO 4 on the basis of density functional calculations. Our work shows unambiguously that the Curie-Weiss temperature  of LiCuVO 4 is negative in the range of 20 K, so that J 2 is substantially stronger in magnitude than J 1 .

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Integration of single-crystal reflections using area multidetectors

Cited by 226 publications

References 5 publications

Field-induced magnetic states in holmium tetraboride

Field-induced magnetic states in holmium tetraboride

New Insights into an Old Molecule: Interaction Energies of Theophylline Crystal Forms

On the Nature of the Spin Frustration in the CuO₂ Ribbon Chains of LiCuVO₄: Crystal Structure Determination at 1.6 K, Magnetic Susceptibility Analysis, and Density Functional Evaluation of the Spin Exchange Constants

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Integration of single-crystal reflections using area multidetectors

Cited by 226 publications

References 5 publications

Field-induced magnetic states in holmium tetraboride

Field-induced magnetic states in holmium tetraboride

New Insights into an Old Molecule: Interaction Energies of Theophylline Crystal Forms

On the Nature of the Spin Frustration in the CuO2 Ribbon Chains of LiCuVO4: Crystal Structure Determination at 1.6 K, Magnetic Susceptibility Analysis, and Density Functional Evaluation of the Spin Exchange Constants

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On the Nature of the Spin Frustration in the CuO₂ Ribbon Chains of LiCuVO₄: Crystal Structure Determination at 1.6 K, Magnetic Susceptibility Analysis, and Density Functional Evaluation of the Spin Exchange Constants