Metals Under Extreme Environments
A new material has been proposed en route to metallic hydrogen, Xe(H2)7 [10, Figure 6]. We intend to study theoretically Ne, Ar, Kr and Xe at different hydrogen concentrations under high pressure. We want to analyze the structural and electronic properties of such systems, to enlarge our comprehension of the basic science behind hydrogen rich systems.
A significant paper (by N. W Ashcroft in 2004)  entitled by “Hydrogen Dominant Metallic Alloys: High Temperature Superconductors?” opened the door for the study of Group 14 hydrides; they (i.e., CH4, SiH4, GeH4, SnH4) have a high atomic fraction of H (80%), and were predicted to metalize as hydrogen-dominant metallic alloys at lower pressures than pure hydrogen. In the past 6 years, a number of studies of Group 14 hydrides were performed, both experimental  and theoretical , have appeared.
- Sci. Thrust Areas: Hydrogen & Hydrogen-Bearing Systems, Metals Under Extreme Environments, Novel Molecular & Covalent Materials, Superconducting, Electronic & Magnetic Materials
- Laboratory or Institution: Cornell University
- Key Partners: Neil W. Ashcroft, Cornell University, Roald Hoffmann, Cornell University
The differences in melting temperatures of transition metals between static and shock measurements are several thousand degrees at Megabar pressures. New measurements using X-ray diffraction, X-ray absorption and the measurement of latent heat related to melting will be performed. Additionally, textural melt features observed on quenched samples (see figure) will be analyzed using electron microscopy.
Study of the phase diagram of hydrogen above one megabar using modified anvil designs with enhanced chemical resistance (with C.S. Zha). An Excimer laser is used to cut dishes into the culets of the diamond anvils, which will then partly be filled with a material that reduces the chemical/physical interaction between hydrogen and diamond.
- Sci. Thrust Areas: Hydrogen & Hydrogen-Bearing Systems, Metals Under Extreme Environments
- Technology Task Force Teams: Extreme P-T Devices, Laser Techniques, Materials for Extreme P-T, Neutrons, Synchrotron Radiation
- Personnel: Reini Boehler, Alex Goncharov, Malcolm Guthrie, Russell Hemley, Ho-kwang (Dave) Mao, Chang-Sheng Zha
- Key Partners: John V. Badding, Penn State
- HPSynC: Guoyin Shen
- National Laboratory Partners: Chris Tulk, SNS