@misc{OstersNilgesSchoeneichetal., author = {Osters, Oliver and Nilges, Tom and Sch{\"o}neich, Michael and Schmidt, Peer and Rothballer, Jan and Pielnhofer, Florian and Weihrich, Richard}, title = {Cd4Cu7As, the first representative of a fully ordered, orthorhombically distorted MgCu2 Laves phase}, series = {Inorganic Chemistry}, volume = {51}, journal = {Inorganic Chemistry}, issn = {1520-510X}, doi = {10.1021/ic3005213}, pages = {8119 -- 8127}, abstract = {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) {\AA}; b = 7.1251(3) {\AA}; c = 5.0895(4) {\AA}. 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 °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 Fd3m̅ with lattice parameter a = 7.0779(8) {\AA}. 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 AB2, 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 {\AA}3 compared to 13 {\AA}3 for Cu) and higher ionicity in bonding.}, language = {en} } @misc{OstersNilgesBachhuberetal., author = {Osters, Oliver and Nilges, Tom and Bachhuber, Frederik and Pielnhofer, Florian and Weihrich, Richard and Sch{\"o}neich, Michael and Schmidt, Peer}, title = {Synthesis and Identification of Metastable Compounds: Black Arsenic—Science or Fiction?}, series = {Angewandte Chemie / International edition}, volume = {51}, journal = {Angewandte Chemie / International edition}, number = {12}, issn = {1521-3773}, doi = {10.1002/anie.201106479}, pages = {2994 -- 2997}, abstract = {Back in black: All metastable and stable phases can be identified for the solid solution arsenic/phosphorus by a combination of quantum-chemical calculations and investigations of the phase formation. Reaction paths for phase formations and transitions in situ were also evaluated. The results show that orthorhombic black arsenic (o-As) is metastable in pure form and has only been previously obtained by stabilizing impurities.}, language = {en} } @misc{SchoeneichHohmannSchmidtetal., author = {Sch{\"o}neich, Michael and Hohmann, Andrea and Schmidt, Peer and Pielnhofer, Florian and Bachhuber, Frederik and Weihrich, Richard and Osters, Oliver and K{\"o}pf, Marianne and Nilges, Tom}, title = {Element allotropes and polyanion compounds of pnicogenes and chalcogenes: stability, mechanisms of formation, controlled synthesis and characterization}, series = {Zeitschrift f{\"u}r Kristallographie - Crystalline Materials}, volume = {232}, journal = {Zeitschrift f{\"u}r Kristallographie - Crystalline Materials}, number = {1-3}, issn = {2194-4946}, doi = {10.1515/zkri-2016-1966}, pages = {91 -- 105}, abstract = {The application of the EnPhaSyn (theoretical Energy diagrams, experimental Phase formation, Synthesis and characterisation) concept is reviewed with respect to prediction of structures and stability of element allotropes and compound polymorphs, their phase formation and transition processes, and their directed synthesis, respectively. Therein, the relative energetical stability (En) of target compounds and possible decomposition are determined from quantum chemical DFT calculations. Phase formation and transition (Pha) is probed by a gas balance method, developed as high temperature gas balance concept. It helped to study the synthesis and stability range of several compounds experimentally. Applications of the concept and synthesis principles (Syn) of non-equilibrium phases are presented for allotropes of P, As, P1-xAsx, as well as binary and ternary compounds including the Zintl and Laves like phases IrPTe, NiP2, CoSbS, NiBiSe, Li0.2CdP2, Cu3CdCuP10, and Cd4Cu7As.}, language = {en} } @misc{NilgesOstersSchmidtetal., author = {Nilges, Tom and Osters, Oliver and Schmidt, Peer and Sch{\"o}neich, Michael and Weihrich, Richard and Bachhuber, Frederik}, title = {Untersuchungen zur Bildung von schwarzem Arsen}, series = {Zeitschrift f{\"u}r Anorganische und Allgemeine Chemie}, volume = {636}, journal = {Zeitschrift f{\"u}r Anorganische und Allgemeine Chemie}, number = {11}, doi = {10.1002/zaac.201008019}, pages = {S. 46}, abstract = {Das Mineralisatorkonzept f{\"u}r Polypniktide, basierend auf PbI2 als Mineralisator, wurde erfolgreich zur Synthese der festen L{\"o}sung von ortho-rhombischem, schwarzen As1-xPx eingesetzt (x = 0.17-1). Die Zellparameter von As0.83P0.17 sind identisch mit den Literaturwerten des As(schwarz). Aus Pulver- und Einkristalldaten bei variabler Zusammensetzung ist es m{\"o}glich, das Zellvolumen und die Gitterparameter von reinem, schwarzen Arsen abzuleiten. Die Analyse der Phasenbildung basiert auf der Bestimmung der Gleichgewichtsdr{\"u}cke der Intermediate Au2P3 und Asgrau sowie von PbI2 im Vergleich zu As1-xPx(schwarz): Die Kondensation erfolgt unterhalb 600 °C aus einer komplexen Gasphase (u.a. AsnP4-n).}, language = {de} }