@misc{PielnhoferSchoeneichLorenzetal., author = {Pielnhofer, Florian and Sch{\"o}neich, Michael and Lorenz, Tobias and Yan, Wenjie and Nilges, Tom and Weihrich, Richard and Schmidt, Peer}, title = {A rational approach to IrPTe - DFT and CalPhaD studies on phase stability, formation and structure of IrPT e}, series = {Zeitschrift f{\"u}r anorganische und allgemeine Chemie}, volume = {641}, journal = {Zeitschrift f{\"u}r anorganische und allgemeine Chemie}, number = {6}, issn = {1521-3749}, doi = {10.1002/zaac.201500149}, pages = {1099 -- 1105}, abstract = {Phase formation, stability, crystal and electronic structures of IrPTe are investigated from experiment and quantum chemical calculations. The phase formation is studied from thermodynamic data and CalPhaD modeling. Applying a high-temperature gas-balance a formation pathway for IrPTe is studied from the elements and the binary parent compounds IrTe2 and IrP2. The obtained paracostibite (CoSbS) type structure contains rarely occurring heteroatomic P-Te dumbbells. The stability of IrPTe and the found structure is studied from DFT calculations with respect to the elements, IrTe2 and IrP2, and possible polymorphs. Probable metastable modifications with XY dumbbells (as known for isoelectronic compounds like CoAsS) are obtained from systematic DFT modelling. Phase transitions are predicted form the equation of states (EOS). According to its electronic band structure IrPTe is predicted as small gap (Eg = 0.5 eV) semiconductor.}, language = {en} } @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{PielnhoferBachhuberSchmidtetal., author = {Pielnhofer, Florian and Bachhuber, Frederik and Schmidt, Peer and Nilges, Tom and Weihrich, Richard}, title = {Mit DFT-Modellierungen zu neuen Polyanionenverbindungen}, series = {Zeitschrift f{\"u}r Anorganische und Allgemeine Chemie}, volume = {638}, journal = {Zeitschrift f{\"u}r Anorganische und Allgemeine Chemie}, number = {10}, doi = {10.1002/zaac.201204137}, pages = {S. 1634}, abstract = {Verbindungen mit ionischen Baueinheiten erweisen sich als geeignete Materialien zur Energie- und Ressourcennutzung. Beispiele sind Li-Elektrodenmaterialien oder neue Thermoelektrika, die aufgrund ihrer Teilstrukturen schaltbar werden. Das Design neuer funktionaler Materialien verlangt dabei nach einem grundlegenden Verst{\"a}ndnis von Struktur-Eigenschafts-Beziehungen, metastabilen Strukturen und Umwandlungen. Dies bedarf des Einsatzes kombinierter experimenteller und theoretischer Methoden. Zur systematischen Erforschung metastabiler Strukturen wurde j{\"u}ngst das Konzept der Strukturvorhersage in Energielandschaften mit ab initio Methoden auf das System P1-xAsx angewandt und mit experimentellen Messungen verkn{\"u}pft. Im n{\"a}chsten Schritt wurden Verbindungen mit ionischen Teilstrukturen des As, Sb, Se und Te untersucht. Modellhaft wurden nun Zintl-Systemen wie IrPTe und PtSnTe neue m{\"o}gliche metastabile Strukturen identifiziert und auf Funktionalisierungen untersucht.}, language = {de} }