Modeling Planetary Interiors in Laser Based Experiments Using Shockless Compression

Hawreliak, J.; Colvin, J. D.; Eggert, J. H.; Kalantar, D. H.; Lorenzana, H. E.; Pollaine, S. M.; Rosolanková, K.; Remington, B. A.; Stölken, James S.; Wark, J. S.

doi:10.1007/s10509-007-9385-z

Cited by 11 publications

(6 citation statements)

References 21 publications

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“…Static-compression diamond-anvil-cell experiments have given us a great deal of information about water ice up to pressures of 0.21 TPa [4][5][6], but this is far below the highest pressures to which water is subjected within planets. Shock wave experiments can reach much higher pressures, and sample precompression [7,8] and ramped compression [9,10] techniques can reduce the resulting temperatures to those more appropriate for planetary science.…”

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Decomposition and Terapascal Phases of Water Ice

Pickard

Martínez-Canales

Needs³

2013

Phys. Rev. Lett.

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Computational searches for stable and metastable structures of water ice and other H:O compositions at TPa pressures have led us to predict that H(2)O decomposes into H(2)O(2) and a hydrogen-rich phase at pressures of a little over 5 TPa. The hydrogen-rich phase is stable over a wide range of hydrogen contents, and it might play a role in the erosion of the icy component of the cores of gas giants as H(2)O comes into contact with hydrogen. Metallization of H(2)O is predicted at a higher pressure of just over 6 TPa, and therefore H(2)O does not have a thermodynamically stable low-temperature metallic form. We have also found a new and rich mineralogy of complicated water ice phases that are more stable in the pressure range 0.8-2 TPa than any predicted previously.

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confidence: 99%

Decomposition and Terapascal Phases of Water Ice

Pickard

Martínez-Canales

Needs³

2013

Phys. Rev. Lett.

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“…That view was challenged recently, when a cagelike diamondoid "N10" structure (space group I43m) was found to be more stable than any other candidate above 263 GPa [31]. Recently, the melting behavior of nitrogen and phases beyond cg-N have also been investigated [10][11][12]30].Recently, dynamical shock wave [36][37][38] and ramped compression experiments [39][40][41] have increasingly been used to investigate materials at TPa pressures. Even more extreme conditions are attainable today in laser ignition experiments [42] and laser-induced microexplosions [43].…”

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Stable All-Nitrogen Metallic Salt at Terapascal Pressures

et al. 2013

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The phase diagram and equation of state of dense nitrogen are of interest in understanding the fundamental physics and chemistry under extreme conditions, including planetary processes, and in discovering new materials. We predict several stable phases of nitrogen at multi-TPa pressures, including a P4/nbm structure consisting of partially charged N(2)(δ+) pairs and N(5)(δ-) tetrahedra, which is stable in the range 2.5-6.8 TPa. This is followed by a modulated layered structure between 6.8 and 12.6 TPa, which also exhibits a significant charge transfer. The P4/nbm metallic nitrogen salt and the modulated structure are stable at high pressures and temperatures, and they exhibit strongly ionic features and charge density distortions, which is unexpected in an element under such extreme conditions and could represent a new class of nitrogen materials. The P-T phase diagram of nitrogen at TPa pressures is investigated using quasiharmonic phonon calculations and ab initio molecular dynamics simulations.

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“…Materials under terapascal pressures are of great interest in planetary science, for example, the pressure at the center of Jupiter is estimated to be about 7 TPa [24]. Recent progress in dynamical shock wave [24][25][26] and ramped compression experiments [27,28] has demonstrated that the terapascal pressure regime is becoming much more accessible.The use of DFT computations combined with searching methods has provided a new route for predicting the structures and energetics of high-pressure phases [23,29,30]. A very recent study of phase transitions, melting, and chemical reactivity in CO 2 found it to dissociate into carbon and oxygen above 33 GPa and 1720 K [31], which adds further motivation for studying pure oxygen at high pressures.…”

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Persistence and Eventual Demise of Oxygen Molecules at Terapascal Pressures

et al. 2012

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Computational searches for structures of solid oxygen under pressures in the multi TPa range have been carried out using density-functional-theory methods. We find that molecular oxygen persists to about 1.9 TPa at which it transforms into a semiconducting square spiral-like polymeric structure (I41/acd) with a band gap of ∼3.0 eV. Solid oxygen forms a metallic zig-zag chain-like structure (Cmcm) at about 3.0 TPa, but the chains in each layer gradually merge as the pressure is increased and a structure of F mmm symmetry forms at about 9.5 TPa in which each atom has four nearest neighbors. The superconducting properties of molecular oxygen do not vary much with compression, although the structure becomes more symmetric. The electronic properties of oxygen have a complex evolution with pressure, swapping between insulating, semiconducting and metallic. Among the simple molecules studied at high pressures, oxygen has attracted particular attention due to its fundamental importance and intriguing properties. [1][2][3][4][5] For example, oxygen is the only known elemental molecule that exhibits magnetism, which adds substantial complexity to its phase diagram. When liquid oxygen is cooled at ambient pressure it undergoes a sequence of transitions to the γ, β and α solid phases at 54.39, 43.76 and 23.88 K, respectively [6]. Upon increase of pressure the monoclinic α-O 2 (C2/m) phase transforms into an orthorhombic δ-O 2 (F mmm) phase at about 3 GPa and to -O 2 at about 10 GPa. The structure of -O 2 has only recently been solved by x-ray diffraction (XRD) studies of single crystal [3] and powder [4] samples, although its vibrational spectrum was reported more than 20 years earlier [7]. The unit cell of -O 2 has C2/m symmetry and contains four O 2 molecules forming O 8 units. Both α and δ-O 2 are antiferromagnetic and the magnetic collapse at the δ-transition was predicted using molecular dynamics simulations [8]. This breakdown of the long-range antiferromagnetic order at about 8 GPa was recently observed in a neutron scattering experiment [2]. Density functional theory (DFT) studies have found another chain-like structure to be energetically slightly more favorable than the O 8 structure [9,10], although it has not been observed in experiments.Recent experiments [5] have shown that insulating -O 2 remains stable up to about 96 GPa before undergoing a continuous displacive and isosymmetric transition to the ζ phase, in agreement with earlier predictions [10]. The metallic ζ phase [11,12] has C2/m symmetry [2] and superconducts at temperatures below 0.6 K [1]. Manybody perturbation theory GW calculations [13,14] have suggested that the metal-insulator transition occurs at lower pressures than the measured -ζ transition pressure of 96 GPa. The above information, however, covers only a small part of the phase diagram and rather little is known about pure oxygen at pressures above 100 GPa.A previous DFT study reported that oxygen molecules persist to at least 250 GPa [10]. It is interesting to speculate about the highest p...

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Modeling Planetary Interiors in Laser Based Experiments Using Shockless Compression

Cited by 11 publications

References 21 publications

Decomposition and Terapascal Phases of Water Ice

Decomposition and Terapascal Phases of Water Ice

Stable All-Nitrogen Metallic Salt at Terapascal Pressures

Persistence and Eventual Demise of Oxygen Molecules at Terapascal Pressures

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