Osmium metal studied under high pressure and nonhydrostatic stress

Estimating the Compressibility of Osmium from Recent Measurements of Ir-Os Alloys under High Pressure

Several fcc- and hcp-structured Ir-Os alloys have been recently studied up to 30 GPa at room temperature by means of synchrotron-based X-ray powder diffraction in diamond anvil cells. Using their bulk moduli, which increase with increasing osmium content, showing a deviation from linearity, and after employing a thermodynamical model, it was concluded that the bulk modulus for osmium is slightly smaller than that for diamond. Here, a similar conclusion is obtained upon employing an alternative model, thus strengthening the conclusion that osmium is the densest but not the most incompressible element. This is particularly interesting for Earth Sciences because it may be of key importance toward clarifying the anomalous elastic properties of the Earth's core.

Containment system for experiments on radioactive and other hazardous materials in a Paris-Edinburgh press

Recent technical developments using the large volume Paris-Edinburgh press platform have enabled x-ray synchrotron studies at high pressure and temperature conditions. However, its application to some materials of interest, such as high hazard materials that require special handling due to safety issues, reactivity, or other challenges, has not been feasible without the introduction of special containment systems to eliminate the hazards. However, introduction of a containment system is challenging due to the requirement to provide full safety containment for operation in the variety of environments available, while not hindering any of the experimental probes that are available for inert sample measurement. In this work, we report on the development and implementation of a full safety enclosure for a Paris-Edinburgh type press. During the initial development and subsequent application stage of work, experiments were performed on both cerium dioxide (CeO2) and uranium (U). This device allows for full implementation of all currently available experimental probes involving the Paris-Edinburgh press at the High Pressure Collaborative Access Team sector of the Advanced Photon Source.

π-stacking intercalation and reductant assisted stabilization of osmium organosol for catalysis and SERS applications

Size-selective, mono-dispersed osmium organosol have been synthesized in toluene which is stabilized by π-stacking intercalation and electrostatic interactions for application in catalysis and SERS studies.

Synthesis of Binary Transition Metal Nitrides, Carbides and Borides from the Elements in the Laser-Heated Diamond Anvil Cell and Their Structure-Property Relations

Transition metal nitrides, carbides and borides have a high potential for industrial applications as they not only have a high melting point but are generally harder and less compressible than the pure metals. Here we summarize recent advances in the synthesis of binary transition metal nitrides, carbides and borides focusing on the reaction of the elements at extreme conditions generated within the laser-heated diamond anvil cell. The current knowledge of their structures and high-pressure properties like high-(p,T) stability, compressibility and hardness is described as obtained from experiments.

Effects of deviatoric stresses in the diamond-anvil pressure cell on single-crystal samples

The nonhydrostatic stress states that are developed in the pressure media within diamond-anvil pressure cells have been investigated by single-crystal X-ray diffraction. Measurements of unit-cell parameters of small single crystals under nonhydrostatic conditions are used to calculate the deviatoric strains and, through knowledge of the elastic tensors of the crystals, the stress state of the media. The results confirm that the stress state is effectively cylindrically symmetrical with the stress parallel to the load axis being greater than the radial stresses. The stress state in a given medium can be predicted and can be used to design a specific response of the lattice parameters of small single crystals to pressure beyond the hydrostatic pressure limit of the pressure medium.