Extending carbon chemistry at high-pressure by synthesis of CaC and CaC with deprotonated polyacene- and para-poly(indenoindene)-like nanoribbons.

Metal carbides are known to contain small carbon units similar to those found in the molecules of methane, acetylene, and allene. However, for numerous binary systems ab initio calculations predict the formation of unusual metal carbides with exotic polycarbon units, [C] rings, and graphitic carbon sheets at high pressure (HP). Here we report the synthesis and structural characterization of a HP-CaC polymorph and a CaC compound featuring deprotonated polyacene-like and para-poly(indenoindene)-like nanoribbons, respectively.

Multicationic Tetrahedra Networks: Alkaline-Earth-Centered Polyhedra and Non-Condensed AlN-Octahedra in the Imidonitridophosphates AEAlPN(NH) (AE=Ca, Sr, Ba).

A series of isostructural imidonitridophosphates AEAlPN(NH) (AE=Ca, Sr, Ba) was synthesized at high-pressure/high-temperature conditions (1400 °C and 5-9 GPa) from alkaline-earth metal nitrides or azides CaN/Sr(N)/Ba(N) and the binary nitrides AlN and PN. NHF served as a hydrogen source and mineralizing agent. The crystal structures were determined by single-crystal X-ray diffraction and feature a three-dimensional network of vertex-sharing PN-tetrahedra forming diverse-sized rings that are occupied by aluminum and alkaline earth ions.

Stabilization of N and N anionic units and 2D polynitrogen layers in high-pressure scandium polynitrides.

Nitrogen catenation under high pressure leads to the formation of polynitrogen compounds with potentially unique properties. The exploration of the entire spectrum of poly- and oligo-nitrogen moieties is still in its earliest stages. Here, we report on four novel scandium nitrides, ScN, ScN, ScN and ScN, synthesized by direct reaction between yttrium and nitrogen at 78-125 GPa and 2500 K in laser-heated diamond anvil cells.

CrSiPN-A Chromium(+IV) Nitridosilicate Phosphate with Amphibole-Type Structure.

The first nitridic analog of an amphibole mineral, the quaternary nitridosilicate phosphate CrSiPN was synthesized under high-pressure high-temperature conditions at 1400 °C and 12 GPa from the binary nitrides CrN, SiN and PN, using NHN and NHF as additional nitrogen source and mineralizing agent, respectively. The crystal structure was elucidated by single-crystal X-ray diffraction with microfocused synchrotron radiation (C2/m, a=9.6002(19), b=17.

Unraveling the Bonding Complexity of Polyhalogen Anions: High-Pressure Synthesis of Unpredicted Sodium Chlorides NaCl and NaCl and Bromide NaBr.

The field of polyhalogen chemistry, specifically polyhalogen anions (polyhalides), is rapidly evolving. Here, we present the synthesis of three sodium halides with unpredicted chemical compositions and structures (10-NaCl, 18-NaCl, and 18-NaBr), a series of isostructural cubic 8-AX halides (NaCl, KCl, NaBr, and KBr), and a trigonal potassium chloride (24-KCl). The high-pressure syntheses were realized at 41-80 GPa in diamond anvil cells laser-heated at about 2000 K.

Hierarchical synchrotron diffraction and imaging study of the calcium sulfate hemihydrate-gypsum transformation.

The mechanism of hydration of calcium sulfate hemihydrate (CaSO·0.5HO) to form gypsum (CaSO·2HO) was studied by combining scanning 3D X-ray diffraction (s3DXRD) and phase contrast tomography (PCT) to determine the spatial and crystallographic relationship between these two phases. From s3DXRD measurements, the crystallographic structure, orientation and position of the crystalline grains in the sample during the hydration reaction were obtained, while the PCT reconstructions allowed visualization of the 3D shapes of the crystals during the reaction.

Mixed Organic Cations Promote Ambient Light-Induced Formation of Metallic Lead in Lead Halide Perovskite Crystals.

One major concern toward the performance and stability of halide perovskite-based optoelectronic devices is the formation of metallic lead that promotes nonradiative recombination of charge carriers. The origin of metallic lead formation is being disputed whether it occurs during the perovskite synthesis or only after light, electron, or X-ray beam irradiation or thermal annealing. Here, we show that the quantity of metallic lead detected in perovskite crystals depends on the concentration and composition of the precursor solution.

Aromatic hexazine [N] anion featured in the complex structure of the high-pressure potassium nitrogen compound KN.

The recent high-pressure synthesis of pentazolates and the subsequent stabilization of the aromatic [N] anion at atmospheric pressure have had an immense impact on nitrogen chemistry. Other aromatic nitrogen species have also been actively sought, including the hexaazabenzene N ring. Although a variety of configurations and geometries have been proposed based on ab initio calculations, one that stands out as a likely candidate is the aromatic hexazine anion [N].

Cubic or Not Cubic? Combined Experimental and Computational Investigation of the Short-Range Order of Tin Halide Perovskites.

Tin-based metal halide perovskites with a composition of ASnX (where A= MA or FA and X = I or Br) have been investigated by means of X-ray total scattering techniques coupled to pair distribution function (PDF) analysis. These studies revealed that that none of the four perovskites has a cubic symmetry at the local scale and that a degree of increasing distortion is always present, in particular when the cation size is increased, i.e.

Revealing Phosphorus Nitrides up to the Megabar Regime: Synthesis of α'-P N δ-P N and PN.

Invited for the cover of this issue are Dominique Laniel (University of Edinburgh), Florian Trybel (University of Linköping), and their colleagues. The image depicts a bridge built of the newly discovered δ-P N solid with the structure featuring PN units, a previously missing connection between the carbon group elements nitrides and chalcogens nitrides. Read the full text of the article at 10.

Ultrasonic Clusterization Process to Prepare [(NNCO)CoCl] as a Novel Double-Open-CoO Cubane Cluster: SXRD Interactions, DFT, Physicochemical, Thermal Behaviors, and Biomimicking of Catecholase Activity.

A novel double-open-cubane (NNCO)CoCl cluster with a CoO core was made available under aqua-ultrasonic open atmosphere conditions for the first time. The ultrasonic clusterization of the (3,5-dimethyl-1-pyrazol-1-yl)methanol (NNCOH) ligand with CoCl·6HO salts in ethanol yielded a high-purity and high-yield cluster product. Energy-dispersive X-ray (EDX), Fourier transform infrared (FT-IR), and ultraviolet (UV)-visible techniques were used to elucidate the clusterization process.

Revealing Phosphorus Nitrides up to the Megabar Regime: Synthesis of α'-P N δ-P N and PN.

Non-metal nitrides are an exciting field of chemistry, featuring a significant number of compounds that can possess outstanding material properties. These properties mainly rely on maximizing the number of strong covalent bonds, with crosslinked XN octahedra frameworks being particularly attractive. In this study, the phosphorus-nitrogen system was studied up to 137 GPa in laser-heated diamond anvil cells, and three previously unobserved phases were synthesized and characterized by single-crystal X-ray diffraction, Raman spectroscopy measurements and density functional theory calculations.

Anionic N Macrocycles and a Polynitrogen Double Helix in Novel Yttrium Polynitrides YN and Y N at 100 GPa.

Two novel yttrium nitrides, YN and Y N , were synthesized by direct reaction between yttrium and nitrogen at 100 GPa and 3000 K in a laser-heated diamond anvil cell. High-pressure synchrotron single-crystal X-ray diffraction revealed that the crystal structures of YN and Y N feature a unique organization of nitrogen atoms-a previously unknown anionic N macrocycle and a polynitrogen double helix, respectively. Density functional theory calculations, confirming the dynamical stability of the YN and Y N compounds, show an anion-driven metallicity, explaining the unusual bond orders in the polynitrogen units.

Materials synthesis at terapascal static pressures.

Theoretical modelling predicts very unusual structures and properties of materials at extreme pressure and temperature conditions. Hitherto, their synthesis and investigation above 200 gigapascals have been hindered both by the technical complexity of ultrahigh-pressure experiments and by the absence of relevant in situ methods of materials analysis. Here we report on a methodology developed to enable experiments at static compression in the terapascal regime with laser heating.

Mixed Dimethylammonium/Methylammonium Lead Halide Perovskite Crystals for Improved Structural Stability and Enhanced Photodetection.

The solvent acidolysis crystallization technique is utilized to grow mixed dimethylammonium/methylammonium lead tribromide (DMA/MAPbBr ) crystals reaching the highest dimethylammonium incorporation of 44% while maintaining the 3D cubic perovskite phase. These mixed perovskite crystals show suppression of the orthorhombic phase and a lower tetragonal-to-cubic phase-transition temperature compared to MAPbBr . A distinct behavior is observed in the temperature-dependent photoluminescence properties of MAPbBr and mixed DMA/MAPbBr crystals due to the different organic cation dynamics governing the phase transition(s).

Nitridic Analogs of Micas AESi P N (NH) (AE=Mg, Mg Ca , Ca, Sr).

We present the first nitridic analogs of micas, namely AESi P N (NH) (AE=Mg, Mg Ca , Ca, Sr), which were synthesized under high-pressure high-temperature conditions at 1400 °C and 8 GPa from the refractory nitrides P N and Si N , the respective alkaline earth amides, implementing NH F as a mineralizer. The crystal structure was elucidated by single-crystal diffraction with microfocused synchrotron radiation, energy-dispersive X-ray spectroscopic (EDX) mapping with atomic resolution, powder X-ray diffraction, and solid-state NMR. The structures consist of typical tetrahedra-octahedra-tetrahedra (T-O-T) layers with P occupying T and Si occupying O layers, realizing the rare motif of sixfold coordinated silicon atoms in nitrides.

Beam heating from a fourth-generation synchrotron source.

The high levels of flux available at a fourth-generation synchrotron are shown to have significant beam heating effects for high-energy X-rays and radiation hard samples, leading to temperature increases of over 400 K with a monochromatic beam. These effects have been investigated at the ID11 beamline at the recently upgraded ESRF Extremely Brilliant Source, using thermal lattice expansion to perform in situ measurements of beam heating. Results showed significant increases in temperature for metal and ceria samples, which are compared with a lumped thermodynamic model, providing a tool for estimating beam heating effects.

Crystal structure determination of a lifelong biopersistent asbestos fibre using single-crystal synchrotron X-ray micro-diffraction.

The six natural silicates known as asbestos may induce fatal lung diseases inhalation, with a latency period of decades. The five amphibole asbestos species are assumed to be biopersistent in the lungs, and for this reason they are considered much more toxic than serpentine asbestos (chrysotile). Here, we refined the atomic structure of an amosite amphibole asbestos fibre that had remained in a human lung for ∼40 years, in order to verify the stability .

Depicting the crystal structure of fibrous ferrierite from British Columbia using a combined synchrotron techniques approach.

The ferrierite crystal structure has often been subject to discussion because of the possible lowering of symmetry from the space group . It mainly occurs in nature with a fibrous crystal habit, and because of the existence of line/planar defects in the framework, texture and preferred orientation effects it has been difficult to obtain an exact crystallographic model based only on the results from powder diffraction data. Therefore, nano-single-crystal diffraction and tomography data have been combined in order to improve the refinement with a meaningful model.

Characterization and assessment of the potential toxicity/pathogenicity of fibrous glaucophane.

In California, the metamorphic blueschist occurrences within the Franciscan Complex are commonly composed of glaucophane, which can be found with a fibrous habit. Fibrous glaucophane's potential toxicity/pathogenicity has never been determined and it has not been considered by the International Agency for Research on Cancer (IARC) as a potential carcinogen to date. Notwithstanding, outcrops hosting fibrous glaucophane are being excavated today in California for building/construction purposes (see for example the Calaveras Dam Replacement Project - CDRP).

High-temperature behavior of natural ferrierite: In-situ synchrotron X-ray powder diffraction study.

In this paper, we report the results of the first study focused on the thermal stability and dehydration dynamics of the natural zeolite mineral ferrierite. A sample from Monastir, Sardinia [(NaKMgCaSr) (AlSi)O·17.86HO; = 19.

Impact of Structural Polymorphism on Ionic Conductivity in Lithium Copper Pyroborate LiCuBO.

The search for high Li-ion conducting ceramics has regained tremendous interest triggered by the renaissance of the all-solid-state battery. Within this context we herein reveal the impact of structural polymorphism of lithium copper pyroborate LiCuBO on its ionic conductivity. Using combined in situ synchrotron X-ray and neutron powder diffraction, a structural and synthetic relationship between α- and β-LiCuBO could be established and its impact on ionic conductivity evolution was followed using electrochemical impedance spectroscopy.

Coherently aligned nanoparticles within a biogenic single crystal: A biological prestressing strategy.

In contrast to synthetic materials, materials produced by organisms are formed in ambient conditions and with a limited selection of elements. Nevertheless, living organisms reveal elegant strategies for achieving specific functions, ranging from skeletal support to mastication, from sensors and defensive tools to optical function. Using state-of-the-art characterization techniques, we present a biostrategy for strengthening and toughening the otherwise brittle calcite optical lenses found in the brittlestar This intriguing process uses coherent nanoprecipitates to induce compressive stresses on the host matrix, functionally resembling the Guinier-Preston zones known in classical metallurgy.