Electrical Conductivity and Metallization of Fluid Hydrogen in the Pressure Range 90-180 GPa(0.9-1.8Mbar)
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Conductivity measurements indicate that hydrogen becomes a metallic fluid at 140 GPa, ninefold initial liquid density, and ∼3000 K. Metallization occurs when the electronic energy gap E<SUB>g</SUB> is reduced by pressure to k<SUB>B</SUB>T . High pressures and temperatures were obtained by a shock wave reverberating in hydrogen between stiff Al<SUB>2</SUB>O<SUB>3</SUB> anvils. Resistivity decreases four orders of magnitude from 93 to 140 GPa and is constant from 140 to 180 GPa. About ∼5% of the H<SUB>2</SUB> molecules are dissociated at metallization . The free-electron Fermi energy is ∼12 ev. The measured conductivities of hydrogen are essentially the same as those of fluid Cs and Rb at 2000 K undergoing the same transition. The transition to the metal occurs at a Mott-scaled density of D<SUB>m</SUB><SUP>1/3</SUP>a*=0. 30, where D<SUB>m</SUB> is the metallization density and a* is the Bohr radius of the molecule. The measured metallic conductivity is in good agreement with (1) the calculated minimum conductivity of a metal, (2) the conductivity of hydrogen calculated with the strong-scattering free-electron model, (3) a preliminary calculation by Louis and Ashcroft using the weak-scattering Ziman model for a molecular liquid metal, and (4) tight-binding molecular dynamics calculations by Lenosky et al.
- The Review of High Pressure Science and Technology
The Review of High Pressure Science and Technology 7, 870-872, 1998
The Japan Society of High Pressure Science and Technology