Solid-State Transformations of Mayenite and Core-Shell Structures of C12A7@C Type at High Pressure, High Temperature Conditions.

Calcium aluminate of a mayenite structure, 12CaO∙7AlO (C12A7), is widely applicable in many fields of modern science and technology. Therefore, its behavior under various experimental conditions is of special interest. The present research aimed to estimate the possible impact of the carbon shell in core-shell materials of C12A7@C type on the proceeding of solid-state reactions of mayenite with graphite and magnesium oxide under High Pressure, High Temperature (HPHT) conditions.

[NiEn](MoO)(WO) Co-Crystals as Single-Source Precursors for Ternary Refractory Ni-Mo-W Alloys.

The co-crystallisation of [NiEn](NO) (En = ethylenediamine) with NaMoO and NaWO from a water solution results in the formation of [NiEn](MoO)(WO) co-crystals. According to the X-ray diffraction analysis of eight single crystals, the parameters of the hexagonal unit cell (space group -31, = 2) vary in the following intervals: a = 9.2332(3)-9.

Fine-Tuning Window Apertures in ZIF-8/67 Frameworks by Metal Ions and Temperature for High-Efficiency Molecular Sieving of Xylenes.

Separation of structurally similar components from their mixtures is one of the most promising applications of metal-organic frameworks (MOFs). A high efficiency of such molecular sieving requires fine tuning of the MOF structure. In this work, we investigate subtle metal- and temperature-induced changes in window dimensions of zeolitic imidazolate frameworks (ZIF-8(Zn) and ZIF-67(Co)) and apply such structural tuning for efficient separation of xylene isomers (-, -, and -xylenes).

Face-Centered Cubic Refractory Alloys Prepared from Single-Source Precursors.

Three binary -structured alloys (-IrPt, -RhPt and -RhPd) were prepared from [Ir(NH)Cl][PtCl], [Ir(NH)Cl][PtBr], [Rh(NH)Cl][PtCl]Cl and [Rh(NH)Cl][PdCl]·HO, respectively, as single-source precursors. All alloys were prepared by thermal decomposition in gaseous hydrogen flow below 800 °C. -IrPt and -RhPd correspond to miscibility gaps on binary metallic phase diagrams and can be considered as metastable alloys.

Synthesis and Crystal Chemistry of Octahedral Rhodium(III) Chloroamines.

Rhodium(III) octahedral complexes with amine and chloride ligands are the most common starting compounds for preparing catalytically active rhodium(I) and rhodium(III) species. Despite intensive study during the last 100 years, synthesis and crystal structures of rhodium(III) complexes were described only briefly. Some [RhCl(NH)] compounds are still unknown.

Precise Measurement and Controlled Tuning of Effective Window Sizes in ZIF-8 Framework for Efficient Separation of Xylenes.

Metal-organic frameworks (MOFs) are the promising nanomaterials for separation of molecules with close dimensions and structures, such as various types of isomers. The efficiency of separation can be greatly enhanced if the apertures of the nanosized windows, controlling the diffusion of a particular molecule inside the cavities, are fine-tuned by external stimuli. We report the new approach for precise measurement of window sizes in ZIF-8 MOF and employ it in efficient separation of xylenes, which is of high practical importance.

Unique Nanomechanical Properties of Diamond-Lonsdaleite Biphases: Combined Experimental and Theoretical Consideration of Popigai Impact Diamonds.

For the first time, lonsdaleite-rich impact diamonds from one of the largest Popigai impact crater (Northern Siberia) with a high concentration of structural defects are investigated under hydrostatic compression up to 25 GPa. It is found that, depending on the nature of a sample, the bulk modulus for lonsdaleite experimentally obtained by X-ray diffraction in diamond-anvil cells is systematically lower and equal to 93.3-100.

Structural Dynamics in a "Breathing" Metal-Organic Framework Studied by Electron Paramagnetic Resonance of Nitroxide Spin Probes.

Reversible structural rearrangements ("breathing") of metal-organic frameworks (MOFs) are interesting and complex phenomena with many potential applications. They are often triggered by small amounts of adsorbed guest molecules; therefore, the guest-host interactions in breathing MOFs are intensively investigated. Due to the sensitivity limitations, most analytical methods require relatively high concentrations of guests in these studies.