High-pressure synthesis in diamond anvil cells can yield unique compounds with advanced properties, but often they are either unrecoverable at ambient conditions or produced in quantity insufficient for properties characterization. Here we report the synthesis of metallic, ultraincompressible ( K 0 = 428(10) GPa), and very hard (nanoindentation hardness 36.7(8) GPa) rhenium nitride pernitride Re 2 (N 2 )(N) 2 . Unlike known transition metals pernitrides Re 2 (N 2 )(N) 2 contains both pernitride N 2 4− and discrete N 3− anions, which explains its exceptional properties. Re 2 (N 2 )(N) 2 can be obtained via a reaction between rhenium and nitrogen in a diamond anvil cell at pressures from 40 to 90 GPa and is recoverable at ambient conditions. We develop a route to scale up its synthesis through a reaction between rhenium and ammonium azide, NH 4 N 3 , in a large-volume press at 33 GPa. Although metallic bonding is typically seen incompatible with intrinsic hardness, Re 2 (N 2 )(N) 2 turned to be at a threshold for superhard materials.

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Owing to intriguing materials properties non-metal nitrides are of special interest for both, solid-state chemistry and materials science. Mixed ternary non-metal nitrides, however, have only been sparsely investigated, as preparative chemistry lacks a systematic access, yet. Herein, we report on the highly condensed boron phosphorus nitride BP N , which was synthesized from (PNCl ) , NH N and h-BN in a high-pressure high-temperature reaction. By increasing partial pressure of HCl during synthesis using NH Cl, single-crystals of BP N up to 80 μm in length were obtained. The unprecedented framework-type structure determined by single-crystal XRD blends structural motifs of both, α-P N and c-BN, rendering BP N a double nitride. The compound was further investigated by Rietveld refinement, EDX, temperature-dependent PXRD, FTIR and solid-state NMR spectroscopy. The formation of BP N through use of reactive precursors exemplifies an innovative access to mixed non-metal nitrides.

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Vortrag anlai3lich der Verleihung der Schleiden-Medaille gibt hiervon Zeugnis.Nicht unerwahnt bleiben sollten auch seine bedeutenden wissenschaftspolitischen Aktivitaten. In vielbeachteten brillanten Vortragen und Publikationen hat er der Offentlichkeit die Stellung der Biowissenschaften an deutschen Universitaten und die Bedeutung der Naturwissenschaft fur unsere Gesellschaft vermittelt.

Carbonates containing CO4 groups as building blocks have recently been discovered. A new orthocarbonate, Sr2CO4 is synthesized at 92 GPa and at a temperature of 2500 K. Its crystal structure was determined by in situ synchrotron single-crystal X-ray diffraction, selecting a grain from a polycrystalline sample. Strontium orthocarbonate crystallizes in the orthorhombic crystal system (space group Pnma) with CO4, SrO9 and SrO11 polyhedra as the main building blocks. It is isostructural to Ca2CO4. DFT calculations reproduce the experimental findings very well and have, therefore, been used to predict the equation of state, Raman and IR spectra, and to assist in the discussion of bonding in this compound.

Under specific experimental circumstances, sputter erosion on semiconductor materials exhibits highly ordered hexagonal dot-like nanostructures. In a recent attempt to theoretically understand this pattern forming process, Facsko et al. [Phys. Rev. B 69, 153412 (2004)] suggested a nonlocal, damped Kuramoto-Sivashinsky equation as a potential candidate for an adequate continuum model of this self-organizing process. In this study we theoretically investigate this proposal by (i) formally deriving such a nonlocal equation as minimal model from balance considerations, (ii) showing that it can be exactly mapped to a local, damped Kuramoto-Sivashinsky equation, and (iii) inspecting the consequences of the resulting non-stationary erosion dynamics.

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