Osters, Oliver and Nilges, Tom and Schoeneich, Michael and Schmidt, Peer and Rothballer, Jan and Pielnhofer, Florian and Weihrich, Richard (2012) Cd4Cu7As, The First Representative of a Fully Ordered, Orthorhombically Distorted MgCu2 Laves Phase. INORGANIC CHEMISTRY, 51 (15). pp. 8119-8127. ISSN 0020-1669,
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The ternary Laves phase Cd4Cu7As is the first intermetallic compound in the system Cu-Cd-As and a representative of a new substitution variant for Laves phases. It crystallizes orthorhombically in the space group Pnnm (No. 58) with lattice parameters a = 9.8833(7) angstrom; b = 7.1251(3) angstrom; c = 5.0895(4) angstrom. All sites are fully occupied within the standard deviations. The structure can be described as typical Laves phase, where Cu and As are forming vertex-linked tetrahedra and Cd adopts the structure motive of a distorted diamond network. Cd4Cu7As was prepared from stoichiometric mixtures of the elements in a solid state reaction at 1000 degrees C. Magnetic measurements are showing a Pauli paramagnetic behavior. During our systematical investigations within the ternary phase triangle Cd-Cu-As the cubic C15-type Laves phase Cd4Cu6.9(1)As1.1(1) was structurally characterized. It crystallizes cubic in the space group Fd3 (m) over bar with lattice parameter a = 7.0779(8) angstrom. Typically for quasi-binary Laves phases Cu and As are both occupying the 16c site. Chemical bonding, charge transfer and atomic properties of Cd4Cu7As were analyzed by band structure, ELF, and AIM calculations. On the basis of the general formula for Laves phases AB(2), Cd is slightly positively charged forming the A substructure, whereas Cu and As represent the negatively charged B substructure in both cases. The crystal structure distortion is thus related to local effects caused by Arsenic that exhibits a larger atomic volume (18 angstrom(3) compared to 13 angstrom(3) for Cu) and higher ionicity in bonding.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | CRYSTAL-STRUCTURE; ELECTRON LOCALIZATION; INTERMETALLIC COMPOUNDS; TERNARY COMPOUNDS; METAL; BOND; REFINEMENT; INDICATOR; SULFIDES; SYSTEM; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Anorganische Chemie > Arbeitskreis Dr. Richard Weihrich |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 08 May 2020 05:49 |
| Last Modified: | 08 May 2020 05:49 |
| URI: | https://pred.uni-regensburg.de/id/eprint/18308 |
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