A Mini Review of Advances in Porous Materials Designing for Hydrogen Isotope Separation.

The separation of mixtures of hydrogen isotopes is one of the greatest challenges of modern separation technology. A newly proposed separation mechanism, the quantum sieving (QS) effect, is expected to achieve high separation factors, the main desired properties for hydrogen isotope separation (HIS). Metal-organic frameworks (MOFs) and zeolites are excellent candidates to study these quantum effects because of their well-defined and tunable pore structure and the potential to introduce strong adsorption sites directly into the framework structure.

Synthesis of large-sized spherical Co-C alloys with soft magnetic properties though a high-pressure solid-state metathesis reaction.

In this work, we report a novel high-pressure solid-state metathesis (HSM) reaction to produce spherical bulk (diameters 2-4 mm) Co-C alloys (CoC and CoC). At 2-5 GPa and 1300 °C, C atoms preferentially occupy the interstitial sites of the face-centered cubic (fcc) Co lattice, leading to the formation of metastable CoC. The CoC decomposes above 1400 °C at 2-5 GPa, C atoms infiltrate the interstitial sites of the fcc Co lattice, saturating the C content in Co, forming an fcc CoC solid solution while the C atoms in excess are found to precipitate in the form of graphite.

High-Pressure Coupling Reactions to Produce a Spherical Bulk ReN/FeN Composite.

We report a novel high-pressure coupling (HPC) reaction that couples the nitridation of Re with high-pressure solid-state metathesis (HPSSM) of FeN to produce a spherical bulk ReN/FeN composite. Compared with conventional methods, upon coupling of the HPSSM reactions, the synthetic pressure for Re nitridation was successfully reduced from 13 to 10 GPa (for ReN) and from 20 to 15 GPa (for ReN). The product ReN species would be surrounded by product FeN, resulting in a spherical bulk ReN/FeN composite ( = 2 or 3).

Rediscovering the intrinsic mechanical properties of bulk nanocrystalline indium arsenide.

Is the inverse Hall-Petch relation in ceramic systems the same as that in metal systems? The premise to explore this subject is the synthesis of a dense bulk nanocrystalline material with clean grain boundaries. By using the reciprocating pressure-induced phase transition (RPPT) technique, compact bulk nanocrystalline indium arsenide (InAs) has been synthesized from a single crystal in a single step, while its grain size is controlled by thermal annealing. The influence of macroscopic stress or surface states on the mechanical characterization has been successfully excluded by combining first-principles calculations and experiments.

Squeezing indium arsenide single crystal to ultrafine nanostructured compact bulk.

Reciprocating pressure-induced phase transition (RPPT) has been proposed as a new approach to synthesize nanostructured bulk materials with clean grain boundary interfaces for structures that undergo reversible pressure-induced phase transitions. The modulation effects on grain size under different cycle numbers of RPPT for InAs were investigated and the initial single-crystal bulk, with a dimensional size of about 30 μm, was transformed into a nanostructure with an average grain size of 7 nm by the utilization of the high-pressure diamond anvil cell (DAC) technique. To verify the DAC findings, compact nanostructured bulk InAs with grain sizes ranging from 2-20 nm (average = 8 nm) and large dimensions (3.

Powder conductor for pressure calibration applied to large volume press under high pressure.

Pressure is the core of high-pressure science and technology, and the accuracy of pressure calibration is of much importance for high-pressure experiments and production. Although the pressure limit of the large volume press (LVP) continues to increase, there are no well solutions for in situ pressure calibration. In this study, using in situ high-pressure electrical performance measurement technology, two ideal calibration standard materials in powder conductors, cadmium phosphide (CdP) and zinc telluride (ZnTe) with stable physical and chemical properties and obvious resistance change, are applied to pressure calibration in the LVP.

Elucidating the Phase Transformation and Metallization Behavior of Zinc Phosphide under High Pressure.

Among the family of IIV-type compounds, zinc phosphide (ZnP) occupies a unique position. As one of the most promising semiconductors well-suited for photovoltaic applications, ZnP has attracted considerable attention. The stability of its structure and properties are of great interest and importance for science and technology.

The effect of size matching between anvils and the pressure transmitting medium on the pressure-generation efficiency and sealing performance for a large volume cubic pressure cell.

Size matching between anvils and the pressure transmitting medium (PTM) is a key factor that affects pressure generation and sealing for a large volume cubic press. In this work, we studied the influence of PTM sizes from 30.5 mm to 34.

Ultrastrong catalyst-free polycrystalline diamond.

Diamond is the hardest naturally occurring material found on earth but single crystal diamond is brittle due to the nature of catastrophic cleavage fracture. Polycrystalline diamond compact (PDC) materials are made by high pressure and high temperature (HPHT) technology. PDC materials have been widely used in several industries.

A new pressurization-insulation and pre-sealing system to improve pressure in cubic press from 6 GPa to 12 GPa.

In this paper, a pressurization-insulation and pre-sealing (PIPS) system is designed to increase the cell pressure of the widely used large volume cubic press without sacrificing cell volume. The sample chamber was sandwiched between a pair of tungsten carbide anvils used as the pressurization system. Ultra-high pressure in the cavity was up to about 12 GPa, and the pressure limit had increased by 100% in contrast with that of an anvil-gasket (AG) system.

Hardness of Polycrystalline Wurtzite Boron Nitride (wBN) Compacts.

Wurtzite boron nitride (wBN), due to its superior properties and many potential practical and scientific applications, such as ideal machining/cutting/milling ferrous and carbide materials, especially as an ideal dielectric substrate material for optical, electronic, and 2-D graphene-based devices, has recently attracted much attention from both academic and industrial fields. Despite decades of research, there is an ongoing debate about if the single-phase wBN is harder than diamond because of the difficulty to make pure wBN material. Here we report the successful synthesis of pure single-phase polycrystalline wurtzite-type boron nitride (wBN) bulk material by using wBN powder as a starting material with a well-controlled process under ultra-high pressure and high temperature.

Experimental study on the pressure-generation efficiency and pressure-seal mechanism for large volume cubic press.

Measuring the pressure of a gasket (P) and cell (P) in situ is the key point to understanding the mechanism of pressure-generation and pressure-seal for the widely used large volume cubic press. However, it is a challenge to measure P due to the large deformation in the gasket zone and the complex rheological behavior of the pressure transmitting medium. Herein, a method of in situ electric resistance measurement has been developed to measure P.

In situ high-pressure measurement of crystal solubility by using neutron diffraction.

Crystal solubility is one of the most important thermo-physical properties and plays a key role in industrial applications, fundamental science, and geoscientific research. However, high-pressure in situ measurements of crystal solubility remain very challenging. Here, we present a method involving high-pressure neutron diffraction for making high-precision in situ measurements of crystal solubility as a function of pressure over a wide range of pressures.

Reciprocating Compression of ZnO Probed by X-ray Diffraction: The Size Effect on Structural Properties under High Pressure.

Zinc oxide, ZnO, an important technologically relevant binary compound, was investigated by reciprocating compress the sample in a diamond anvil cell using in situ high-pressure synchrotron X-ray diffraction at room temperature. The starting sample (∼200 nm) was compressed to 20 GPa and then decompressed to ambient condition. The quenched sample, with average grain size ∼10 nm, was recompressed to 20 GPa and then released to ambient condition.

Pressure calibration in solid pressure transmitting medium in large volume press.

The pressure limit in the large-volume-press (LVP) is increasing, but the in situ pressure calibration in LVP is still not a well resolved problem. The variation of the electrical resistance of the manganin with pressure in a hydrostatic condition is well known and is widely used in the pressure calibration in LVP. However, the hydrostatic pressure condition is hard to be maintained for the unavoidable solidification of the pressure transmitting medium (PTM) with pressure increasing.

Structures, Phase Transformations, and Dielectric Properties of BiTaO Ceramics.

Low (α)- and high-temperature (β) forms of BiTaO have attracted much attention due to their dielectric and photocatalytic properties. In the present work, a third form, the so-called HP-BiTaO, was synthesized at high temperature and pressure. The phase evolution, phase transformations, and dielectric properties of α- and β-BiTaO and HP-BiTaO ceramics are studied in detail.

Phase transition induced strain in ZnO under high pressure.

Under high pressure, the phase transition mechanism and mechanical property of material are supposed to be largely associated with the transformation induced elastic strain. However, the experimental evidences for such strain are scanty. The elastic and plastic properties of ZnO, a leading material for applications in chemical sensor, catalyst, and optical thin coatings, were determined using in situ high pressure synchrotron axial and radial x-ray diffraction.

Elastic, magnetic and electronic properties of iridium phosphide Ir2P.

Cubic (space group: Fmm) iridium phosphide, Ir2P, has been synthesized at high pressure and high temperature. Angle-dispersive synchrotron X-ray diffraction measurements on Ir2P powder using a diamond-anvil cell at room temperature and high pressures (up to 40.6 GPa) yielded a bulk modulus of B0 = 306(6) GPa and its pressure derivative B0' = 6.

Unusual Mott transition in multiferroic PbCrO3.

The Mott insulator in correlated electron systems arises from classical Coulomb repulsion between carriers to provide a powerful force for electron localization. Turning such an insulator into a metal, the so-called Mott transition, is commonly achieved by "bandwidth" control or "band filling." However, both mechanisms deviate from the original concept of Mott, which attributes such a transition to the screening of Coulomb potential and associated lattice contraction.

The Hardest Superconducting Metal Nitride.

Transition-metal (TM) nitrides are a class of compounds with a wide range of properties and applications. Hard superconducting nitrides are of particular interest for electronic applications under working conditions such as coating and high stress (e.g.

Revisit of Pressure-Induced Phase Transition in PbSe: Crystal Structure, and Thermoelastic and Electrical Properties.

Lead selenide, PbSe, an important lead chalcogenide semiconductor, has been investigated using in-situ high-pressure/high-temperature synchrotron X-ray diffraction and electrical resistivity measurements. For the first time, high-quality X-ray diffraction data were collected for the intermediate orthorhombic PbSe. Combined with ab initio calculations, we find a Cmcm, InI-type symmetry for the intermediate phase, which is structurally more favorable than the anti-GeS-type Pnma.

A new molybdenum nitride catalyst with rhombohedral MoS2 structure for hydrogenation applications.

Nitrogen-rich transition-metal nitrides hold great promise to be the next-generation catalysts for clean and renewable energy applications. However, incorporation of nitrogen into the crystalline lattices of transition metals is thermodynamically unfavorable at atmospheric pressure; most of the known transition metal nitrides are nitrogen-deficient with molar ratios of N:metal less than a unity. In this work, we have formulated a high-pressure route for the synthesis of a nitrogen-rich molybdenum nitride through a solid-state ion-exchange reaction.

Carbon coated face-centered cubic Ru-C nanoalloys.

Carbon-encapsulated ruthenium-carbon (Ru-C) nanoalloys were synthesized by dynamic shocks. The Ru-C alloy shows a new fcc structure different from the original hcp structure of metal Ru. This fcc phase is assigned to a Ru32C4 solid solution with a lattice parameter of 3.

Unusual compression behavior of nanocrystalline CeO₂.

The x-ray diffraction study of 12 nm CeO2 was carried out up to ~40 GPa using an angle dispersive synchrotron-radiation in a diamond-anvil cell with different pressure transmitting medium (PTM) (4:1 methanol: ethanol mixture, silicone oil and none) at room temperature. While the cubic fluorite-type structure CeO2 was retained to the highest pressure, there is progressive broadening and intensity reduction of the reflections with increasing pressure. At pressures above 12 GPa, an unusual change in the compression curve was detected in all experiments.

Synthetic route to metal nitrides: high-pressure solid-state metathesis reaction.

We report a general synthetic route to well-crystallized metal nitrides through a high-pressure solid-state metathesis reaction (HPSSM) between boron nitride (BN) and ternary metal oxide A(x)M(y)O(z) (A = alkaline or alkaline-earth metal and M = main group or transition metal). On the basis of the synthetic metal nitrides (Fe3N, Re3N, VN, GaN, CrN, and W(x)N) and elemental products (graphite, rhenium, indium, and cobalt metals), the HPSSM reaction has been systematically investigated with regard to its general chemical equation, reaction scheme, and characteristics, and its thermodynamic considerations have been explored by density functional theory (DFT) calculations. Our results indicate that pressure plays an important role in the synthesis, which involves an ion-exchange process between boron and the metal ion, opening a new pathway for material synthesis.