<i>PROMETHEUS</i>. A program system for investigation of anharmonic thermal vibrations in crystals

Zucker, U. H.; Perenthaler, E.; Kuhs, Werner F.; Bachmann, Rainer; Schulz, H.

doi:10.1107/s0021889883010560

Cited by 215 publications

(53 citation statements)

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“…A spherical absorption correction with μίΙ = 1.8 was applied too using program SPHERE of the PROMETHEUS sy stem [ 1 ]. The absorption correction improved the iiint from 0.187 to 0.142.…”

Section: Source Of Materialsmentioning

confidence: 99%

“…Within these products crystals of the composition CoCrGe (EDX-analysis) were found and isolated. The figure shows an euhedral crystal of about 0.5 mm diameter.For the data collection a smaller crystal without well developed faces was used.The empirical absorption correction was based on a function of the mean intensity of the imaging plate versus angle phi using program DECAY of the Stoe IPDS software package.A spherical absorption correction with μίΙ = 1.8 was applied too using program SPHERE of the PROMETHEUS sy stem [ 1 ]. The absorption correction improved the iiint from 0.187 to 0.142.…”

mentioning

confidence: 99%

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Crystal structure of cobalt chromium germanium, CoCrGe

Wirringa

Wartchow

Binnewies

2000

Zeitschrift Für Kristallographie - New Crystal Structures

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CoCrGe, hexagonal, P^mmc (No. 194), a = 4.092(1) Ä, c = 5.145(2) Ä, V= 74.6 Ä 3 , Z= 2, R e (F) = 0.049, wR m (F 2 ) = 0.097, Γ= 300 K. Source of materialSingle crystals of cobalt chromium germanium were grown by chemical vapour transport in a closed quartz ampoule. Iodine was used as transporting agent. The metals and the transporting agent were heated at 1148 Κ for seven days to homogenize the source material. The chemical vapour transport was performed at 1073 Κ -> 1223 Κ. After seven days, the deposition of single crystals with different compositions can be observed in the crystallisation zone. Within these products crystals of the composition CoCrGe (EDX-analysis) were found and isolated. The figure shows an euhedral crystal of about 0.5 mm diameter.For the data collection a smaller crystal without well developed faces was used.The empirical absorption correction was based on a function of the mean intensity of the imaging plate versus angle phi using program DECAY of the Stoe IPDS software package.A spherical absorption correction with μίΙ = 1.8 was applied too using program SPHERE of the PROMETHEUS sy stem [ 1 ]. The absorption correction improved the iiint from 0.187 to 0.142. DiscussionThe structure of CoCrGe can be derived from the Ni2ln type. From our X-ray analysis we conclude that position 2a is occupied by Cr, 2c by Co and 2d by Ge. Co and Ge may be interchanged. The high temperature phase of CoGeMn, e.g., is known to have this structure [2], According to the TYPIX database [3] the structure belongs to the BeZrSi-type, but BeZrSi has a much higher da ratio. Related phases in the binary system Co-Ge are Coi.7sGe (called "Co2Ge" [4]) and CosGe3, but in these phases at least one occupation factor for Co is <1. Therefore these phases have a smaller cell volume. The lattice constants of "Co2Ge" are reported as a = 3.940 Ä and c = 5.018 A. The higher displacement factor of Co and the lower one of Cr suggest that there might be a mixed occupation of positions 2a and 2c, for instance (0.9 Cr + 0.1 Co) on la and (0.9 Co + 0.1 Cr) on 2c. But trials to refine this model yield only very small amounts of the minor element in both positions with large errors and no significant reduction of the, where an explanation is given for the large value of Bco). If one refines anisotropic displacement parameters thermal ellipsoids are obtained which are comparable to those in CoGeMn (HT), namely elongated ellipsoids for Co and Ge and a flattened ellipsoid for the 2a metal with respect to the hexagonal c axis. For this comparison the parameters of CoGeMn (HT) given in [2] have to be transformed by an origin shift of 01/41/4 followed by a multiplication with matrix 002/011 /-100, because in [2] the structure is described in terms of an orthorhombic cell which simplifies the comparison to the low temperature phase of CoGeMn. The refinement of anisotropic displacement parameters improves the R values considerably, but because of the small number of observed reflections in the unique data set the isotropic structure m...

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“…A spherical absorption correction with μίΙ = 1.8 was applied too using program SPHERE of the PROMETHEUS sy stem [ 1 ]. The absorption correction improved the iiint from 0.187 to 0.142.…”

Section: Source Of Materialsmentioning

confidence: 99%

mentioning

confidence: 99%

Crystal structure of cobalt chromium germanium, CoCrGe

Wirringa

Wartchow

Binnewies

2000

Zeitschrift Für Kristallographie - New Crystal Structures

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“…For the structure refinement we used the PROMETHEUS program package in a version for data sets obtained for twinned crystals. 47 The twinning leads to correlations between some u 11 and u 22 mean-square displacements, which were taken into consideration by introducing constraints.…”

Section: Prmentioning

confidence: 99%

X-ray absorption spectroscopy of detwinnedPrxY1−

et al. 1997

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UvA-DARE is a service provided by the library of the University of Amsterdam (http://dare.uva.nl) UvA-DARE (Digital Academic Repository)X-ray absorption spectroscopy of detwinned PrxY1-xBa2Cu3O7-y single crystals: electronic structure and hole distribution Merz, M.; Nücker, N.; Pellegrin, E.; Schweiss, P.; Schuppler, S.; Kielwein, M.; Knupfer, M.; Golden, M.S.; Fink, J. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Substituting Y in orthorhombic ͑Y,R)Ba 2 Cu 3 O 7 by any rare-earth element R has generally little effect on the superconducting properties. For RϭPr, however, superconductivity is completely suppressed. To understand this effect we have studied the unoccupied electronic structure of Pr x Y 1Ϫx Ba 2 Cu 3 O 7Ϫy (xϭ0.0, 0.4, 0.8) using polarization-dependent O 1s near-edge x-ray absorption spectroscopy of detwinned single crystals. We identify the hole states in the CuO 2 planes and the CuO 3 chains and give estimates of the relative contributions of the O 2p x , O 2p y , and O 2p z orbitals to these states. Along with the comparison of oxygen-rich (yϷ0.1) to the oxygen-depleted materials (yϷ0.9), this allows a test of the current theoretical explanations for the Pr-induced suppression of superconductivity. While we can rule out models involving hole filling or charge transfer between the planes and the chains, our data are consistent with approaches based on Pr 4f -O 2p hybridization. ͓S0163-1829͑97͒03313-4͔

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“…After data reduction with the program PROMETHEUS (Zucker, Perenthaler, Kuhs, Bachmann & Schulz, 1983) reflections with I > 30 were used for least-squares refinements with the program CRYLSQ of the XRAY system (Stewart, Kundell & Baldwin, 1970). Scattering factors have been taken from Cromer & Mann (1968).…”

Section: Methodsmentioning

confidence: 99%

Influence of high hydrostatic pressure on the crystal structure of BaFCl in the pressure range up to 6.5 GPa

Beck¹,

Limmer²,

Denner³

et al. 1983

Acta Crystallogr Sect B

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High-pressure X-ray diffraction measurements were made with BaFC1 single crystals (space group P4/nmm) using a diamond-anvil cell on a four-circle diffractometer (six data sets, 30 to 50 reflections, R values ranging from 2.5 to 5.0%). This compound does not show a pressure-induced phase transition up to 6.5 GPa at ambient temperatures. At lower pressures the compressibility of the c axis is larger than that of the a axis. At 2 GPa the compressibility becomes isotropic and at higher pressures again anisotropic, but now with an increasing c/a ratio. Such effects of pressure and the changes in positional parameters are discussed in comparison with the known structural data for a whole series of PbFCl-type compounds. Changes in the ion 'size' are accompanied by distortions of the structural framework leading to a more efficient packing. While the Madelung number decreases during this process, the relative loss of ionic lattice energy is compensated for by an increase in interactions due to polarization, which can be traced by the movement of the Ba 2+ ions within their coordination sphere. IntroduetlonIt is remarkable that mixed-anion compounds MFX with larger cations M mostly crystallize with the same structural arrangement regardless of the large differences in size and polarizability of the atoms found in such compounds. It has been stated that this variety in constituents leads to different 'branches' of the structure type, of which one -the PbFC1 type ( Fig. 1) -contains compounds with mainly ionic interactions, whereas another -coined as anti-Fe2As type -is encountered with compounds showing strongly covalent character, e.g. UPS (Flahaut, 1974;Johnson & Jeitschko, 1973). ' 0108-7681/83/040401-04501.50 We have emphasized that, within its field of existence, the PbFC1 type itself shows marked variations with respect to crystal geometry and even bonding. The structural differences within this arrangement, ranging from a coordination lattice (found with MOC1, MFCI and MHC1 compounds) to a layer structure (MOI, MFI, MHI), have been discussed by B~irnighausen, Brauer & Schultz (1965).A detailed analysis of well refined structures of fluorohalides (Beck, 1979) has shown an interesting correlation between positional parameters and the polarizability of the constituent ions. In the course of these studies it was our aim to trace the changes in bonding type induced by higher pressures by the same minute analysis of structural details.High-pressure X-ray investigations using powder specimens of fluorochlorides and -bromides of Eu, Sin, Pb and alkaline earths have shown no structural rearrangement up to pressures between 5 and 10 GPa (1 GPa = 10 kbar) (Beck, 1978a). The lattice constants of these compounds decrease linearly with pressure except for BaFC1, which was therefore chosen for further studies under high pressure using single crystals. © 1983 International Union of Crystallography INFLUENCE OF HYDROSTATIC PRESSURE ON THE STRUCTURE OF BaFC1Experimental BaFC1 crystals were prepared by sintering of the bin...

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PROMETHEUS. A program system for investigation of anharmonic thermal vibrations in crystals

Cited by 215 publications

References 3 publications

Crystal structure of cobalt chromium germanium, CoCrGe

Crystal structure of cobalt chromium germanium, CoCrGe

X-ray absorption spectroscopy of detwinnedPrxY1−

Influence of high hydrostatic pressure on the crystal structure of BaFCl in the pressure range up to 6.5 GPa

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