TY - GEN A1 - Osters, Oliver A1 - Nilges, Tom A1 - Schöneich, Michael A1 - Schmidt, Peer A1 - Rothballer, Jan A1 - Pielnhofer, Florian A1 - Weihrich, Richard T1 - Cd4Cu7As, the first representative of a fully ordered, orthorhombically distorted MgCu2 Laves phase T2 - Inorganic Chemistry N2 - 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) Å; b = 7.1251(3) Å; c = 5.0895(4) Å. 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) Å. 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 Å3 compared to 13 Å3 for Cu) and higher ionicity in bonding. Y1 - 2012 UR - http://pubs.acs.org/doi/abs/10.1021/ic3005213 U6 - https://doi.org/10.1021/ic3005213 SN - 1520-510X VL - 51 SP - 8119 EP - 8127 ER - TY - GEN A1 - Günther, David A1 - Beckmann, Jens A1 - Schöneich, Michael A1 - Schmidt, Peer A1 - Klepel, Olaf T1 - Porous concrete as a template for the synthesis of porous carbon materials T2 - Carbon N2 - The potential of industrial porous concrete for using as a template for the synthesis of porous carbon materials has been investigated. Carbon replicas of porous concrete have been prepared by carbonization of sucrose. The pores of the resulting carbon materials range from the macropore to the micropore region, pointing to a hierarchy. Y1 - 2012 UR - http://www.sciencedirect.com/science/article/pii/S000862231200173X?np=y U6 - https://doi.org/10.1016/j.carbon.2012.02.039 SN - 0008-6223 VL - 50 IS - 8 SP - 3092 EP - 3116 ER - TY - GEN A1 - Schmidt, Peer A1 - Schöneich, Michael A1 - Bawohl, Melanie A1 - Nilges, Tom A1 - Weihrich, Richard T1 - Thermal analysis detecting equilibrium conditions: The use of the high temperature gas balance for thermogravimetric measurements T2 - Journal of Thermal Analysis and Calorimetry N2 - Several methods are established in thermal analysis to investigate phase formation, phase transition, and decomposition reactions. The analysis of phase equilibria with volatile components is particularly feasible by using standard method of thermogravimetry. Hardly any investigations of phase formation reactions are possible to realize if one of the components is lost by vaporization. By using the “High-Temperature Gas-Balance” (HTGB), the vapor phase is enclosed in a silica ampoule and thus forms an equilibrium gas phase in permanent contact with the solid phase. The measurement signal Δmmeas is caused by change of the leverage of the horizontal balance support during evaporation and condensation. The application of the HTGB allows the analysis of solid–gas equilibria in the working range from 0.01 till 15 bar at temperatures up to 1,100 °C. The first comparison of evaporation reactions determined by standard thermogravimetric analyses and by measurements using the HTGB is given for the inorganic systems: P, As, SeO2, PtI2, and Hg/I. KW - High-Temperature Gas-Balance KW - Thermogravimetry KW - Vapor pressure KW - Equilibrium measurements Y1 - 2012 UR - http://www.akademiai.com/doi/pdf/10.1007/s10973-011-2107-3 U6 - https://doi.org/10.1007/s10973-011-2107-3 SN - 1572-8943 VL - 110 IS - 3 SP - 1511 EP - 1521 ER - TY - GEN A1 - Osters, Oliver A1 - Nilges, Tom A1 - Bachhuber, Frederik A1 - Pielnhofer, Florian A1 - Weihrich, Richard A1 - Schöneich, Michael A1 - Schmidt, Peer T1 - Synthesis and Identification of Metastable Compounds: Black Arsenic—Science or Fiction? T2 - Angewandte Chemie / International edition N2 - 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. KW - arsenic KW - metastable phases KW - phase formation KW - phosphorus KW - solid-state structures Y1 - 2012 UR - http://onlinelibrary.wiley.com/doi/10.1002/anie.201106479/abstract U6 - https://doi.org/10.1002/anie.201106479 SN - 1521-3773 VL - 51 IS - 12 SP - 2994 EP - 2997 ER - TY - GEN A1 - Schöneich, Michael A1 - Schmidt, Peer T1 - Kinetics of phase formation in solid - gas reactions: Iron and Arsenic T2 - Zeitschrift für Anorganische und Allgemeine Chemie N2 - Based on the experience of thermo-chemical studies on a High-Temperature Gas-Balance a time dependent analysis has been developed for the investigations of the kinetics of solid-gas reactions. The course of solid-gas reactions can be examined unambiguously by separation of the initial solids. By this setup the visualization of different stages of solid-gas reaction (vaporization, phase formation) becomes feasible. Time dependent analysis of the formation of FeAs results in an assignment of the underlying principles of kinetics derived from the conversion factor α. KW - Arsenic KW - High-temperature Gas-balance KW - Thermal analysis Y1 - 2012 UR - http://onlinelibrary.wiley.com/doi/10.1002/zaac.201204026/full U6 - https://doi.org/10.1002/zaac.201204026 VL - 638 IS - 10 SP - S. 1579 ER - TY - GEN A1 - Schmidt, Peer A1 - Schöneich, Michael A1 - Nilges, Tom A1 - Weihrich, Richard T1 - Identification of Metastable States in Heterogeneous Phase Formation T2 - Zeitschrift für Anorganische und Allgemeine Chemie KW - Phosphorus KW - High-temperature Gas-balance Y1 - 2012 UR - http://onlinelibrary.wiley.com/doi/10.1002/zaac.201204134/full U6 - https://doi.org/10.1002/zaac.201204134 N1 - Poster VL - 638 IS - 10 SP - S. 1633 ER - TY - CHAP A1 - Beckmann, Jens A1 - Günther, David A1 - Schmidt, Peer A1 - Schöneich, Michael A1 - Klepel, Olaf T1 - Template assisted synthesis of porous carbon materials using porous concrete as a template T2 - 5th International Sypmosium on “Carbon on Catalysis”, Books of abstracts, Bressanone/Brixen, 2012 Y1 - 2012 ER -