An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

AbstractThe title solid solution (0 ≤ x ≤ 1) is prepared from the elements (Ta bomb, 1323 K, 24 h) and characterized by XANES, and synchrotron and neutron powder diffraction.

The solid solution Yb(x)Ca(1-x)C2 (0 ≤ x ≤ 1) was synthesized by reaction of the elements at 1323 K. The crystal structures within this solid solution, as elucidated from synchrotron powder diffraction data, depend on x and exhibit some interesting features that point to a structure dependent valence state of Yb. Compounds with x ≥ 0.75 crystallize in the tetragonal CaC2 type structure (I4/mmm, Z = 2) and obey Vegard's law; for x ≤ 0.75 the monoclinic ThC2 type structure (C2/c, Z = 4) is found, which coexists with the monoclinic CaC2-III type structure (C2/m, Z = 4) for x ≤ 0.25. The monoclinic modifications show a strong deviation from Vegard's law. Their unit cell volumes are remarkably larger than expected for a typical Vegard system. HERFD-XANES spectroscopic investigations reveal that different Yb valence states are responsible for the observed volume anomalies. While all tetragonal compounds contain mixed-valent Yb with ∼75% Yb(3+) (similar to pure YbC2), all monoclinic modifications contain exclusively Yb(2+). Therefore, Yb(x)Ca(1-x)C2 is a very rare example of a Yb containing compound showing a strong structure dependence of the Yb valence state. Moreover, temperature dependent synchrotron powder diffraction, neutron TOF powder diffraction, and HERFD-XANES spectroscopy experiments reveal significant Yb valence changes in some compounds of the Yb(x)Ca(1-x)C2 series that are induced by temperature dependent phase transitions. Transitions from the tetragonal CaC2 type structure to the monoclinic ThC2 or the cubic CaC2-IV type structure (Fm3m, Z = 4) are accompanied by drastic changes of the mean Yb valence from ∼2.70 to 2.0 in compounds with x = 0.75 and x = 0.91. Finally, the determination of lattice strain arising inside the modifications with ordered dumbbells (ThC2 and CaC2 type structures) by DSC measurements corroborated our results concerning the close relationship between crystal structure and Yb valence in the solid solution Yb(x)Ca(1-x)C2.

The valence state of Yb in YbC(2) was analyzed using high-energy-resolution fluorescence detection (HERFD) X-ray absorption near-edge structure (XANES) spectroscopy and time-of-flight neutron powder diffraction to clarify a controversy in the literature. The unit cell volume of YbC(2) suggests a mixed Yb valence, which was formerly determined to be 2.8 by magnetization measurements and paramagnetic neutron scattering techniques. However, the nature of the intermediate valence was not clearly established. Both homogeneous and heterogeneous mixed valences were assumed in different publications. The temperature-dependent behavior of the valence state was only predicted, albeit not explicitly studied. In this work, the valence state of Yb in YbC(2) is, therefore, investigated thoroughly by HERFD-XANES spectroscopy at low and high temperatures. Our measurements result in an average Yb valence of 2.81 that is temperature-independent from 15 to 1123 K. These findings are confirmed by neutron powder diffraction experiments, which reveal a constant C-C distance of 128.7(9) pm in a temperature range from 5 to 100 K. A significant temperature dependence of the Yb valence state in YbC(2) can, therefore, be excluded by our experimental results.

ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionNEXTORIGINAL ARTICLEThis notice is a correctionCorrection to Structural Phase Transitions in EuC2Derk Wandner, Pascal Link, Oliver Heyer, John Mydosh, Mahmoud A. Ahmida, Mohsen M. Abd-Elmeguid, Manfred Speldrich, Heiko Lueken, and Uwe Ruschewitz*Cite this: Inorg. Chem. 2011, 50, 6, 2703Publication Date (Web):February 10, 2011Publication History Published online10 February 2011Published inissue 21 March 2011https://pubs.acs.org/doi/10.1021/ic200013zhttps://doi.org/10.1021/ic200013zcorrectionACS PublicationsCopyright © 2011 American Chemical Society. This publication is available under these Terms of Use. Request reuse permissions This publication is free to access through this site. Learn MoreArticle Views417Altmetric-Citations5LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail PDF (606 KB) Get e-AlertscloseSupporting Info (3)»Supporting Information Supporting Information Get e-Alerts

Improved energy-optimized (6s5p4d) and (7s6p5d) primitive valence basis sets have been derived for energy-consistent scalar-relativistic 4f-in-core pseudopotentials of the Stuttgart-Cologne variety modeling divalent lanthanides with a \(4\hbox{f}^{n+1}\) occupation (n = 0–13 for La–Yb). Segmented contracted basis sets covering the range of polarized double-, triple-, and quadruple-zeta quality, augmented by 2f1g correlation sets, were created for use in molecular calculations. The basis sets contain smaller (4s4p3d) and (5s5p4d) primitive subsets, which are designed in particular for solid state calculations of crystals containing divalent lanthanide ions. Hartree–Fock, density functional theory and coupled cluster results obtained with the new basis sets for lanthanide atomic ionization potentials as well as of geometry optimizations of various test molecules, i.e. selected lanthanide mono- and dihydrides, mono- and difluorides, and monooxides, show a satisfactory agreement with experimental data as well as with corresponding scalar-relativistic all-electron results. Core-polarization potentials are found to improve the results, especially for the atomic first and second ionization potentials.

A solid solution EuxSr1-xC2 (0 <= x <= 1) was synthesized by direct reaction of the elements at 1123 K. The crystal structures of these compounds, investigated by synchrotron powder diffraction, depend upon x. For x > 0.5 the monoclinic ThC2 type structure (C2/c, Z = 4) is observed and for x <= 0.5 the ThC2 type structure coexists with the tetragonal CaC2 type structure (I4/mmm, Z = 2). The unit cell volumes per formula unit of all EuxSr1-xC2 compounds show perfect Vegard behavior, which is due to the almost identical ionic radii of Eu2+ and Sr2+. Mossbauer spectroscopic investigations indeed reveal that europium is in the divalent state over the whole composition range.

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Pure EuC(2), free of EuO impurities, was obtained by the reaction of elemental europium with graphite at 1673 K. By means of synchrotron powder diffraction experiments, the structural behavior was investigated in the temperature range from 10 to 1073 K. In contrast to former results, EuC(2) crystallizes in the ThC(2) type structure (C2/c, Z = 4) at room temperature. A tetragonal modification (I4/mmm, Z = 2) is only observed in a very small temperature range just below the transition to a cubic high-temperature modification (Fm3m, Z = 4) at 648 K. DTA/TG investigations confirm these results. According to Raman spectroscopy, EuC(2) contains C(2)(2-) ions (nu(C[triple bond]C) = 1837 cm(-1)). The divalent character of Eu is confirmed by the results of magnetic susceptibility measurements and (151)Eu Mossbauer spectroscopy. In these measurements a transition to a ferromagnetic state with T(C) = 15 K is observed, which is in reasonable agreement with literature data. Above T(C) EuC(2) is a semiconductor according to measurements of the electric resistivity vs temperature, again in contrast to former results. Around T(C) a sharp maximum of the electric resistivity vs temperature curve was observed, which collapses on applying external magnetic fields. The observed CMR effect (colossal magnetoresistance) is much stronger than that reported for other EuC(2) samples in the literature. These investigations explicitly show the influence of sample purity on the physical and even structural properties of EuC(2).

Zeitschrift für anorganische und allgemeine ChemieVolume 634, Issue 11 p. 2060-2060 Poster YbxCa1-xC2 : Solid solutions with interesting structural properties Pascal Link, Pascal Link Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 KölnSearch for more papers by this authorUwe Ruschewitz, Corresponding Author Uwe Ruschewitz uwe.ruschewitz@uni-koeln.de Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 KölnInstitut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 KölnSearch for more papers by this author Pascal Link, Pascal Link Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 KölnSearch for more papers by this authorUwe Ruschewitz, Corresponding Author Uwe Ruschewitz uwe.ruschewitz@uni-koeln.de Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 KölnInstitut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 KölnSearch for more papers by this author First published: 28 August 2008 https://doi.org/10.1002/zaac.200870103Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume634, Issue11September 2008Pages 2060-2060 RelatedInformation

Zeitschrift für anorganische und allgemeine ChemieVolume 634, Issue 11 p. 2060-2060 Poster YbxCa1-xC2 : Solid solutions with interesting structural properties Pascal Link, Pascal Link Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 KölnSearch for more papers by this authorUwe Ruschewitz, Corresponding Author Uwe Ruschewitz uwe.ruschewitz@uni-koeln.de Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 KölnInstitut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 KölnSearch for more papers by this author Pascal Link, Pascal Link Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 KölnSearch for more papers by this authorUwe Ruschewitz, Corresponding Author Uwe Ruschewitz uwe.ruschewitz@uni-koeln.de Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 KölnInstitut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 KölnSearch for more papers by this author First published: 28 August 2008 https://doi.org/10.1002/zaac.200870103Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume634, Issue11September 2008Pages 2060-2060 RelatedInformation