Search Results

You searched for all publications:

with publication states 'Published (Approved)'

Search Again...

These results only include publications that have been reviewed and processed by Diamond Light Source. To also view papers that have not yet been processed click here.

You can use the folder icon under Actions to collate papers as required. You can then click on View Folder in the left-hand navigation to review and/or download your folder.

Exact matches
Related results

5 items found (0 items not approved), displaying all items.1

Instruments / Technical Area	Publication Details	Published
I15-Extreme Conditions	Stabilization of boron carbide via silicon doping J E Proctor , Vineet Bhakhri , R Hao , Tim Prior , Thomas Scheler , Eugene Gregoryanz , M Chhowalla , Finn Giuliani Journal Of Physics: Condensed Matter 27 (1), 015401 DOI: 10.1088/0953-8984/27/1/015401 Diamond Proposal Number(s): [6833] Show Abstract ▼ Abstract: Boron carbide is one of the lightest and hardest ceramics, but its applications are limited by its poor stability against a partial phase separation into separate boron and carbon. Phase separation is observed under high non-hydrostatic stress (both static and dynamic), resulting in amorphization. The phase separation is thought to occur in just one of the many naturally occurring polytypes in the material, and this raises the possibility of doping the boron carbide to eliminate this polytype. In this work, we have synthesized boron carbide doped with silicon. We have conducted a series of characterizations (transmission electron microscopy, scanning electron microscopy, Raman spectroscopy and x-ray diffraction) on pure and silicon-doped boron carbide following static compression to 50 GPa non-hydrostatic pressure. We find that the level of amorphization under static non-hydrostatic pressure is drastically reduced by the silicon doping.	Jan 2015
I15-Extreme Conditions	High-Pressure Synthesis and Characterization of Iridium Trihydride Thomas Scheler , Miriam Marqués , Zuzana Konôpková , Christophe L. Guillaume , Ross T. Howie , Eugene Gregoryanz Physical Review Letters 111 (21) DOI: 10.1103/PhysRevLett.111.215503 PMID: 24313503 Show Abstract ▼ Abstract: We have performed in situ synchrotron x-ray diffraction studies of the iridium-hydrogen system up to 125 GPa. At 55 GPa, a phase transition in the metal lattice from the fcc to a distorted simple cubic phase is observed. The new phase is characterized by a drastically increased volume per metal atom, indicating the formation of a metal hydride, and substantially decreased bulk modulus of 190 GPa (383 GPa for pure Ir). Ab initio calculations show that the hydrogen atoms occupy the face-centered positions in the metal matrix, making this the first known noninterstitial noble metal hydride and, with a stoichiometry of IrH3, the one with the highest volumetric hydrogen content. Computations also reveal that several energetically competing phases exist, which can all be seen as having distorted simple cubic lattices. Slow kinetics during decomposition at pressures as low as 6 GPa suggest that this material is metastable at ambient pressure and low temperatures.	Nov 2013
I15-Extreme Conditions	Nanocrystalline tungsten hydrides at high pressures Thomas Scheler , Feng Peng , Christophe L. Guillaume , Ross Howie , Yanming Ma , Eugene Gregoryanz Physical Review B 87 (18) DOI: 10.1103/PhysRevB.87.184117 Show Abstract ▼ Abstract: A combined experimental and theoretical study has been carried out on the synthesis and characterization of tungsten hydride at high pressures. We confirm the synthesis of tungsten monohydride at above 25 GPa and 300 K. At higher pressures, hydrogen content is found to increase and ab-initio calculations reveal the formation of overstoichiometric tungsten hydride WHn with n ∼ 1 1 3 . Synchrotron x-ray diffraction and transmission electron microscopy (TEM) measurements demonstrate the formation of a nanocrystalline microstructure upon hydrogenation. TEM micrographs show elongated grains with diameters of ∼20 nm, a structure similar to nanocrystalline diamond.	May 2013
I15-Extreme Conditions	High-pressure synthesis of noble metal hydrides Christian Donnerer , Thomas Scheler , Eugene Gregoryanz The Journal Of Chemical Physics 138 (13) DOI: 10.1063/1.4798640 Show Abstract ▼ Abstract: The formation of hydride phases in the noble metals copper, silver, and gold was investigated by in situ x-ray diffraction at high hydrogen pressures. In the case of copper, a novel hexagonal hydride phase, Cu 2H, was synthesised at pressures above 18.6 GPa. This compound exhibits an anti-CdI2-type structure, where hydrogen atoms occupy every second layer of octahedral interstitial sites. In contrast to chemically produced CuH, this phase does not show a change in compressibility compared to pure copper. Furthermore, repeated compression (after decomposition of Cu 2H) led to the formation of cubic copper hydride at 12.5 GPa, a phenomenon attributed to an alteration of the microstructure during dehydrogenation. No hydrides of silver (up to 87 GPa) or gold (up to 113 GPa) were found at both room and high temperatures.	Apr 2013
I15-Extreme Conditions	On the effects of high temperature and high pressure on the hydrogen solubility in rhenium Thomas Scheler , Olga Degtyareva , Eugene Gregoryanz The Journal Of Chemical Physics 135 (21) DOI: 10.1063/1.3652863 Show Abstract ▼ Abstract: In situx-ray diffraction experiments on rhenium hydride compressed up to 46 GPa reveal a hydrogen solubility (x) significantly larger than the previously assumed saturation limit of x ? 0.38(4). In the layered anti-CdI2-type structure of rhenium hydride, the hydrogen solubility was found to increase to x ? 0.5 at 15 GPa over time. When heated to temperatures above 420 K at pressures above 23 GPa, rhenium hydride undergoes an isomorphous phase transition into the NiAs-type structure accompanied by an increase in hydrogen solubility to x ? 0.85. The formation of fully stoichiometric rhenium hydride is discussed.	Dec 2011

Publications Database

Search Results

You searched for all publications:

Search Again...

Subject Areas (check all that apply) select all

Instruments used to collect data (check all that apply) select all

Collaborations involved (check all that apply) select all

Diamond Offline Facilities used

Relevant Technical Areas (check all that apply) select all

Menu for Anonymous User