A simplified procedure for orientation of single crystals of any structure

Krahl-Urban, Bernhard; Butz, R.; Preuss, E.

doi:10.1107/s0567739473000197

Cited by 16 publications

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“…The crystal structure is usually known but the crystal orientation is unknown and determined by refinement from the experimentally observed Laue reflection positions [59,92,93]. The strain tensor can be determined as well.…”

Section: Appendix a X-ray Diffractionmentioning

confidence: 99%

X-Ray Diffraction under Extreme Conditions at the Advanced Light Source

Stan

Beavers

Kunz

et al. 2018

QuBS

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Abstract:The more than a century-old technique of X-ray diffraction in either angle or energy dispersive mode has been used to probe materials' microstructure in a number of ways, including phase identification, stress measurements, structure solutions, and the determination of physical properties such as compressibility and phase transition boundaries. The study of high-pressure and high-temperature materials has strongly benefitted from this technique when combined with the high brilliance source provided by third generation synchrotron facilities, such as the Advanced Light Source (ALS) (Berkeley, CA, USA). Here we present a brief review of recent work at this facility in the field of X-ray diffraction under extreme conditions, including an overview of diamond anvil cells, X-ray diffraction, and a summary of three beamline capabilities conducting X-ray diffraction high-pressure research in the diamond anvil cell.

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Section: Appendix a X-ray Diffractionmentioning

confidence: 99%

X-Ray Diffraction under Extreme Conditions at the Advanced Light Source

Stan

Beavers

Kunz

et al. 2018

QuBS

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“…Since the first simulation of a Laue pattern by KrahI-Urban, Butz & Preuss (1973), many programs have been written for the simulation and/or indexation of Laue diagrams. Some of them are referenced by Marin, Cintas & Di~guez (1994).…”

Section: The Category Computer Program Abstracts Provides a Rapid Meamentioning

confidence: 99%

“…(1996) (Received 7 Febrary 1996; accepted 9 April 1996) The crystallographic problem: The use of computer programs has considerably simplified the determination of unknown crystal orientation, avoiding the classical method using stereographic projection and Wulff nets. Simulations may also be useful for teaching purposes.Since the first simulation of a Laue pattern by KrahI-Urban, Butz & Preuss (1973), many programs have been written for the simulation and/or indexation of Laue diagrams. Some of them are referenced by Marin, Cintas & Di~guez (1994).…”

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confidence: 99%

Crystallographers

1996

J Appl Cryst

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The category Computer Program Abstracts provides a rapid means of communicating up-to-date information concerning both new programs or systems and significant updates to existing ones. Following normal submission, a Computer Program Abstract will be reviewed by one or two members of the IUCr Appl. Cryst. (1985). 18, t89-t90].J. AppL Cryst. (1996) (Received 7 Febrary 1996; accepted 9 April 1996) The crystallographic problem: The use of computer programs has considerably simplified the determination of unknown crystal orientation, avoiding the classical method using stereographic projection and Wulff nets. Simulations may also be useful for teaching purposes.Since the first simulation of a Laue pattern by KrahI-Urban, Butz & Preuss (1973), many programs have been written for the simulation and/or indexation of Laue diagrams. Some of them are referenced by Marin, Cintas & Di~guez (1994).Up to now, it seems that no modern general program dedicated to the processing of diffraction data has been available on UNIX workstations, except the LAUEGEN package of Campbell (1995). However, LAUEGEN is a large program, requiring a lot of disk space, involved in a suite whose aim is the computation of integrated intensities with a view to structure resolution, while LAUEX is only a small simulation/indexation program for everyday work. Method of solution:LAUEX is a userfriendly program, with an X Window graphical interface. The user enters data in the menus and chooses options by clicking on buttons or moving sliders with the mouse. The data may be saved for later use.LAUEX performs the following tasks: (i) Simulation of a Laue diagram, from knowledge of the orientation of the crystal, the cell parameters and the position © 1996 International Union of Crystallography Printed in Great Britain -all rights reserved of the detector. Note that LAUEX is not limited to the transmission and reflection cases, but that the position of the detector may be located anywhere on a sphere centred on the crystal. This feature has been introduced especially for work carried out at a synchrotron. If the structure of the crystal is known, the program may evaluate the intensities of the Laue spots and draws them as spots whose size is proportional to their intensity. The parameters taken into account for this computation are those described by Preuss (1979) (except for the crystal shape), plus the response curve of the detector.(ii) Indexation of an experimental Laue diagram, by the knowledge of the cell parameters and the position of a number of spots of low index. The indexation procedure has been suggested by Riquet & Bonnet (1979) and has already been used by Laugier & Filhol (1983).(iii) Alignment of a crystallographic direction along an axis of the apparatus (usually the one pointing towards the X-ray source), or rotation of the crystal.(iv) Storing of the simulated diagram as a PostScript file, or printing directly to a laser printer.On-line help is available if a World Wide Web (WWW) browser is installed on the machine.Software enviro...

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“…Remarquons de plus que ces six taches ne se diff6rencient pas ais6ment des autres: leur intensit6 n'est gu6re plus forte que celle des autres, elles ne sont pas situ6es au croisement de nombreuses hyperboles et elles ne sont pas nettement 61oign6es des autres taches. I1 est donc peu probable qu'un chercheur disposant des programmes cit6s aboutisse imm6diate-ment ~ la bonne indexation.Une autre m6thode, plus compl&e, pr6sentant le grand avantage de traiter les taches avec la mesure exp6rimentale de leur intensit6 int6gr6e, est due /l Krahl-Urban, Butz & Preuss (1973 Cette note pr6sente un nouvel algorithme qui permet de r6duire certains inconv6nients des m6thodes cit6es. I1 s'applique aussi bien aux clich6s en retour qu'en…”

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Dépouillement par ordinateur des clichés de diffraction obtenus par la méthode de Laue

Riquet¹,

Bonnet²

1979

J Appl Cryst

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A computation method is presented which allows a rapid indexing of any unknown spot pattern obtained by back-reflection or transmission Laue methods. The Cartesian coordinates of n spots are measured in an orthonormal frame referred to the photographic film. Two spots 1 and 2 separated by a wide angular distance ~" are carefully chosen. Their indices are assumed to be less than 5. The set (E) of all the pairs of planes (hlklll) and (h2kz12) making an angle ~ close to ~" is then computed. Since the pair of reflecting planes related to spots 1 and 2 belongs to (E), each computed pair of planes is tried, in order to determine the orientation of the crystal and to check whether the coordinates of the (n-2) other spots can be matched to dense planes of indices less than 8. If the uncertainty of the measurements is high or if n is too low, this method gives the possible orientations for the crystal. Plane indices less than 8 have been identified in cubic, tetragonal and orthorhombic crystals.La d6termination de l'orientation des cristaux est souvent effectu6e par la m6thode de Laue en retour (Cullity, 1967). Les taches de diffraction visibles sur un clich6 sont habituellement index6es par essais et erreurs, m6thode qui devient vite fastidieuse si le cristal n'est pas cubique ou a une orientation quelconque. Les premiers, Heizmann & Baro (1967) ont syst6matis6 cette m6thode et parviennent fi fournir l'indexation des taches dans le cas off le faisceau de RX est perpendiculaire ~un plan r6ticulaire du cristal. Huang, Christensen & Block (1971) utilisent, pour un cristal d'orientation quelconque, les coordonn6es cart6siennes de n taches de diffraction, mesur6es dans un rep6re solidaire au plan du film, et comparent les distances angulaires s6parant les taches du film ~ celles calcul6es th6oriquement fi partir des indices des plans. Cependant, cette m6thode comporte certains inconv6nients: elle n'est applicable pour l'instanf qu'aux cristaux cubiques et hexagonaux; si l'un des indices de Miller de l'une des n taches ~ indexer est sup6rieur /t 3, aucune solution n'est possible; le calcul conduit/t une seule orientation possible du cristal alors qu'il peut y avoir plusieurs orientations compatibles avec le groupe des n taches mesur6es et les incertitudes de Malgr6 ces derni6res transformations un tel programme est peu satisfaisant, essentiellement parce que, sous peine d'atteindre des temps de calcul prohibitif, n doit &re limit6 h 5, les indices de Miller des n taches choisies doivent &re au plus 6gaux ~ 3 et le nombre de taches non identifiables doit &re limit6 ~ 1. I1 est ainsi impossible d'indexer convenablement certains clich6s de Laue en retour m6me pour des orientations cristallines simples. Par exemple dans l'un de nos clich6s de Laue en retour (Fig. 1) d'un cristal quadratique centr6 A12Cu (0) dont la face perpendiculaire au faisceau de RX est (100), six taches seulement sur les 19 taches visibles ont leurs trois indices plus petits que 5. Remarquons de plus que ces six taches ne se diff6rencient pas ais6me...

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A simplified procedure for orientation of single crystals of any structure

Cited by 16 publications

References 1 publication

X-Ray Diffraction under Extreme Conditions at the Advanced Light Source

X-Ray Diffraction under Extreme Conditions at the Advanced Light Source

Crystallographers

Dépouillement par ordinateur des clichés de diffraction obtenus par la méthode de Laue

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