Disks of YBa2Cu3O7 shocked to 10 GPa pressures

Nellis, W. J.; Weir, Sam; Hinsey, N.; Balachandran, U.; Kramer, Matt; Raman, R. V.

doi:10.1063/1.46427

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“…Critical current density of a superconductor is measured by the size of its magnetic hysteresis M(H) at a given applied magnetic field H. Oxygen disorder and microcracks induced by shock compression reduce M. However, after annealing the shocked sample in oxygen, the magnetic hysteresis at 1 kOe and 70 K is about 20% greater than the value before shock at 7 GPa (Nellis et al 1994). Annealing heals microcracks, reorders oxygen in the lattice, and changes the total number and relative concentrations of dislocations and stacking faults.…”

Section: Experimental Methodsmentioning

confidence: 99%

Dynamic compression of materials: metallization of fluid hydrogen at high pressures

2006

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Dynamic high pressure is 1 GPa (10 kbar) or greater with a rise time and a duration ranging from 1 ps (10 −12 s) to 1 µs (10 −6 s). Today it is possible in a laboratory to achieve pressures dynamically up to ∼500 GPa (5 Mbar) and greater, compressions as much as ∼15fold greater than initial density in the case of hydrogen and temperatures from ∼0.1 up to several electronvolts (11 600 K). At these conditions materials are extremely condensed semiconductors or degenerate metals. Temperature can be tuned independently of pressure by a combination of shock and isentropic compression. As a result, new opportunities are now available in condensed matter physics at extreme conditions. The basic physics of the dynamic process, experimental methods of generating and diagnosing matter at these extreme conditions and a technique to recover metastable materials intact from ∼100 GPa shock pressures are discussed.Results include (i) generation of pressure standards at static pressures up to ∼200 GPa (2 Mbar) at 300 K, (ii) single-shock compression of small-molecular fluids, including resolution of the recent controversy over the correct shock-compression curve of liquid D 2 at 100 GPa pressures, (iii) the first observations of metallization of fluid hydrogen, nitrogen and oxygen compressed quasi-isentropically at 100 GPa pressures, (iv) implications for the interiors of giant planets within our solar system, extrasolar giant planets and brown dwarfs discovered recently and the equation of state of deuterium-tritium in inertial confinement fusion (ICF) and (v) prospects of recovering novel materials from extreme conditions, such as metastable solid metallic hydrogen. Future research is suggested.

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Section: Experimental Methodsmentioning

confidence: 99%