Semiconducting non-molecular nitrogen up to 240 GPa and its low-pressure stability

  title={Semiconducting non-molecular nitrogen up to 240 GPa and its low-pressure stability},
  author={Mikhail I. Eremets and Russell J. Hemley and Ho-kwang Mao and Eugene Gregoryanz},
The triple bond of diatomic nitrogen has among the greatest binding energies of any molecule. At low temperatures and pressures, nitrogen forms a molecular crystal in which these strong bonds co-exist with weak van der Waals interactions between molecules, producing an insulator with a large band gap. As the pressure is raised on molecular crystals, intermolecular interactions increase and the molecules eventually dissociate to form monoatomic metallic solids, as was first predicted for… 

Formation of xenon-nitrogen compounds at high pressure

Through a series of optical spectroscopy and x-ray diffraction experiments, this work demonstrates the formation of a novel van der Waals compound formed from binary Xe-N2 mixtures at pressures as low as 5 GPa.

Evidence for a high-pressure isostructural transition in nitrogen

Understanding the high-pressure behaviors of diatomic molecules (H2, O2, N2, etc) is one of the most basic as well as important objective in high-pressure physics. Under high pressure diatomic

Structural transformation of molecular nitrogen to a single-bonded atomic state at high pressures.

The major transformation of this diatomic phase into the single-bonded (polymeric) phase, recently determined to have the cubic gauche structure (cg-N), proceeds as a first-order transition with a volume change of 22%.

Metallization and molecular dissociation of dense fluid nitrogen

The authors explore, by pulsed laser heating in a diamond anvil cell and optical measurements, the metallization and non-molecular states of nitrogen in a previously unexplored domain above 1 Mbar and at 2000-7000K.

Hexagonal Layered Polymeric Nitrogen Phase Synthesized near 250 GPa.

X-ray diffraction and Raman vibrational data reveal a tetragonal lattice (P4_{2}bc) that matches the predicted hexagonal layered polymeric nitrogen (HLP-N) structure.

Intermolecular Interactions in Highly Disordered, Confined Dense N2.

A rationale for the polymerization of a number molecules occurring in the microchannels of noncatalytic zeolites under pressure is found, where the pressure threshold is found to be very similar to that observed in bulk samples.

A New Allotrope of Nitrogen as High-Energy Density Material.

The N6 molecule is a charge-transfer complex with an open-chain structure containing both single and triple bonds that leads to a much higher cohesive energy for the predicted crystal compared to solid N2.

Raman study of pressure-induced dissociative transitions in nitrogen

Polymerization of nitrogen in sodium azide.

The high-pressure behavior of nitrogen in NaN(3) was studied to 160 GPa at 120-3300 K using Raman spectroscopy, electrical conductivity, laser heating, and shear deformation methods, finding that at pressures above 19 GPa a new phase appeared, indicating a strong coupling between the azide ions.

Single-bonded cubic form of nitrogen

The polymeric nitrogen with the theoretically predicted cubic gauche structure (cg-N) represents a new class of single-bonded nitrogen materials with unique properties such as energy capacity: more than five times that of the most powerfully energetic materials.



Theoretical study of the molecular-to-nonmolecular transformation of nitrogen at high pressures.

  • MartínNeeds
  • Chemistry, Physics
    Physical review. B, Condensed matter
  • 1986
It is concluded that the results predict a transition to a nonmolecular structure at experimentally accessible pressures, in apparent disagreement with recent experiments in which no such transition was found up to a reported pressure of 1.3 Mbar.

Solid hydrogen at 342 GPa: no evidence for an alkali metal

Solid hydrogen, an electrical insulator, is predicted to become an alkali metal under extreme compression, although controversy surrounds the pressure required to achieve this. The electrical

Structure and bandgap closure in dense hydrogen

D density functional calculations within the local density approximation are reported that predict a range of densities for hydrogen where a paired or molecular metallic state may be energetically preferred, and the pressures required to effect the transition are shown to change significantly when the gaps are corrected by approximate inclusion of many-electron effects.

Calculation of the pressure-induced insulator-metal transition of nitrogen

Previous theoretical predictions of metallization below 1000 kbar are in apparent disagreement with the experimental fact that nitrogen is observed to remain a molecular solid up to 1300 kbar. The 0

Phase transition in solid molecular hydrogen at ultrahigh pressures.

  • HemleyMao
  • Chemistry, Physics
    Physical review letters
  • 1988
Spontaneous Raman spectra demonstrate that the solid undergoes a structural phase transformation beginning at 145 GPa at 77 K, as evidenced by an abrupt discontinuity in the intramolecular vibron frequency as a function of pressure.

Pressure dissociation of solid nitrogen under 1 Mbar.

The calculated 35% volume change raises the possibility of a large barrier to dissociation and extensive regions of metastability in diamond-anvil cells.

Superconductivity in oxygen

Among the simple diatomic molecules, oxygen is of particular interest because it shows magnetism at low temperatures. Moreover, at pressures exceeding 95 GPa (∼0.95 Mbar), solid molecular oxygen

Optical studies of nitrogen to 130 GPa.

Nitrogen is observed to remain a molecular solid up to 130 GPa, contrary to recent theoretical predictions of metallization below 100 GPa. Raman scattering reveals three new phases at 20, 66, and 100

Optical evidence for a nonmolecular phase of nitrogen above 150 GPa

Optical absorption measurements reveal that the semiconducting absorption edge responsible for the change of color is characterized by the presence of a wide Urbach-like tail and a high-energy (Tauc) region, consistent with the dissociation of molecular nitrogen into a nonmolecular (possibly amorphous) phase.