Structural and electronic properties of sodium azide at high pressure: A first principles study

Zhang, Meiguang; Yin, Ketao; Zhang, Xinxin; Wang, Hui; Li, Quan; Wu, Zhijian

doi:10.1016/j.ssc.2013.01.032

Cited by 50 publications

(52 citation statements)

References 33 publications

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“…The structure search correctly finds the α-phase of NaN 3 with the symmetry C2/m at 0.5 GPa in agreement with experiment, while at 30 GPa it correctly produces the I4/mcm polymorph of NaN 3 [21,25]. At 60 GPa, the P6/m-Na 2 N 6 structure featuring N 6 rings is found to be the lowest enthalpy phase with a 1:3 sodium to nitrogen ratio, consistent with previous calculations [21].…”

Section: Resultssupporting

confidence: 85%

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Sodium pentazolate: A nitrogen rich high energy density material

Steele

Oleynik

2016

Chemical Physics Letters

125

128

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Sodium pentazolates NaN 5 and Na 2 N 5 , new high energy density materials, are discovered during first principles crystal structure search for the compounds of varying amounts of elemental sodium and nitrogen. The pentazole anion (N − 5 ) is stabilized in the condensed phase by sodium Na + cations at pressures exceeding 20 GPa, and becomes metastable upon release of pressure. The sodium azide (NaN 3 ) precursor is predicted to undergo a chemical transformation above 50 GPa into sodium pentazolates NaN 5 and Na 2 N 5 . The calculated Raman spectrum of NaN 5 is in agreement with the experimental Raman spectrum of a previously unidentified substance appearing upon compression and heating of NaN 3 .

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Section: Resultssupporting

confidence: 85%

“…The PBE functional has been previously shown to give reliable results for sodium azide [13,21]. In VASP calculations, ultrasoft pseudopotentials [22] with inner core radii of 1.757Å for Na and 0.873Å for N and plane wave basis sets are used with an energy cutoff of 600 eV and a 0.05Å −1 k-point sampling.…”

Section: Computational Detailsmentioning

confidence: 99%

Sodium pentazolate: A nitrogen rich high energy density material

Steele

Oleynik

2016

Chemical Physics Letters

125

128

View full text Add to dashboard Cite

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“…It reveals that extra atoms play an important role in stabilizing N 6 ring. More recently, a P 6/ m structure containing N 6 ring has been also predicted in LiN 3 131415 and NaN 3 16. Thus, the P 6/ m structure is considered in KN 3 .…”

Section: Resultsmentioning

confidence: 91%

Pressure-induced planar N6 rings in potassium azide

Zhang

Lin

et al. 2014

Sci Rep

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The first-principles method and the evolutionary algorithm are used to identify stable high pressure phases of potassium azide (KN3). It has been verified that the stable phase with space group I4/mcm below 22 GPa, which is consistent with the experimental result, will transform into the C2/m phase with pressure increasing. These two phases are insulator with anions. A metallic phase with P6/mmm symmetry is preferred above 40 GPa, and the N atoms in this structure form six-membered rings which are important for understanding the pressure effect on anions and phase transitions of KN3. Above the studied pressure (100 GPa), a polymerization of N6 rings may be obtained as the result of the increasing compactness.

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“…On the other hand, metal azides are expected to polymerize at pressures considerably lower than pure N 2 due to the "chemical pre-compression" caused by metal elements. [4][5][6][7][8] Besides the too high synthesis pressure, other obstacle of application of polymeric nitrogen is the stability at ambient conditions. 9 Metal elements in azides are also expected to act as electronic donors and improve the stability of polymeric nitrogen.…”

Section: Introductionmentioning

confidence: 99%

Polymerization of nitrogen in cesium azide under modest pressure

Wang

Zhu

et al. 2014

The Journal of Chemical Physics

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Alkali metal azides can be used as starting materials in the synthesis of polymeric nitrogen, a potential high-energy-density material. The structural evolutionary behaviors of nitrogen in CsN3 have been studied up to 200 GPa using particle swarm optimization structure search combining with density functional theory. Three stable new phases with C2/m, P21/m, and P-1 structure at pressure of 6, 13, and 51 GPa are identified for the first time. The phase transition to chain like structure (P-1 phase) occurs at a modest pressure 51 GPa, the azide ions N3 (-) (linear chains of three N atoms with covalent bonds and interact weakly with each other) begin to show remarkable polymeric N properties in the CsN3 system. Throughout the stable pressure range, the structure is metallic and consists of N atoms in sp(2) hybridizations. Our study completes the structural evolution of CsN3 under pressure and reveals that the introduced Cs atoms are responsible for the decreased synthesis pressure comparing to pure molecular nitrogen under compression.

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Structural and electronic properties of sodium azide at high pressure: A first principles study

Cited by 50 publications

References 33 publications

Sodium pentazolate: A nitrogen rich high energy density material

Sodium pentazolate: A nitrogen rich high energy density material

Pressure-induced planar N6 rings in potassium azide

Polymerization of nitrogen in cesium azide under modest pressure

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