High pressure synchrotron x-ray diffraction and Raman scattering studies of ammonium azide

Wu, Xiaoxin; Cui, Hong; Zhang, Jian; Cong, Rongjuan; Zhu, Hongyang; Cui, Qiliang

doi:10.1063/1.4798336

Cited by 23 publications

(49 citation statements)

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“…1 It also exhibits extensive hydrogen bonding between ammonium cation and terminal nitrogen atoms of azide anions. 2,3 Unlike the alkali, alkaline-earth and transition metal azides which are either ionic or covalent, 4 AA is found to have mixed bonding with unique properties.…”

Section: Introductionmentioning

confidence: 99%

Phase stability and lattice dynamics of ammonium azide under hydrostatic compression

Yedukondalu

Vaitheeswaran

Anees

et al. 2015

Phys. Chem. Chem. Phys.

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We have investigated the effect of hydrostatic pressure and temperature on phase stability of hydro-nitrogen solids using dispersion corrected Density Functional Theory calculations. From our total energy calculations, Ammonium Azide (AA) is found to be the thermodynamic ground state of N 4 H 4 compounds in preference to Trans-Tetrazene (TTZ), Hydro-Nitrogen Solid-1 (HNS-1) and HNS-2 phases. We have carried out a detailed study on structure and lattice dynamics of the equilibrium phase (AA). AA undergoes a phase transition to TTZ at around ∼ 39-43 GPa followed by TTZ to HNS-1 at around 80-90 GPa under the studied temperature range of 0-650 K. The accelerated and decelerated compression of a and c lattice constants suggest that the ambient phase of AA transforms to a tetragonal phase and then to a low symmetry structure with less anisotropy up on further compression. We have noticed that the angle made by Type-II azides with c-axis shows a rapid decrease and reaches a minimum value at 12 GPa, and thereafter increases up to 50GPa. Softening of the shear elastic moduli is suggestive of a mechanical instability of AA under high pressure. In addition, we have also performed density functional perturbation theory calculations to obtain the vibrational spectrum of AA at ambient as well as at high pressures. Further, we have made a complete assignment of all the vibrational modes which is in good agreement with the experimental observations at ambient pressure. Also the calculated pressure dependent IR spectra show that the N-H stretching frequencies undergo a red and blue-shift corresponding to strengthening and weakening of hydrogen bonding, respectively below and above 4 GPa. Intensity of the N-H asymmetric stretching mode B 2u is found to diminish gradually and the weak coupling between NH 4 and N 3 ions makes B 1u and B 3u modes to be degenerate with progression of pressure up to 4 GPa which causes weakening of hydrogen bonding and these effects may lead to a structural phase transition in AA around 4 GPa. Furthermore, we have also calculated the phonon dispersion curves at 0 and 6 GPa and no soft phonon mode is observed under high pressure.

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Section: Introductionmentioning

confidence: 99%

Phase stability and lattice dynamics of ammonium azide under hydrostatic compression

Yedukondalu

Vaitheeswaran

Anees

et al. 2015

Phys. Chem. Chem. Phys.

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“…Both of these studies reveal that vdW-TS method is good enough to reproduce the structural properties of HZA and AA which are closely comparable with the experimental data. 16,20 Therefore, in the present study, we have also used the vdW-TS method to obtain the ground state structures by optimizing the lattice geometry and fractional co-ordinates HZA, respectively, when compared with the experimental results. Here "-" and "+" represent the under-and over-estimation of the calculated results when compared to experimental data.…”

Section: Computational Detailsmentioning

confidence: 99%

“…In addition, understanding the high pressure behavior of HNS become an emerging field of research. 10 16 A series of experimental 15,16 and theoretical 10 14,17,18 studies were reported to explore the electronic structure, mechanical, hydrogen bonding and possible structural phase transitions in HNS under hydrostatic compression. Ammonium Azide (AA) with nitrogen content of 93.3% by weight is proposed to form a polymeric nitrogen (which is a green high energy density material known till date) under extreme conditions.…”

Section: Introductionmentioning

confidence: 99%

“…TMAA19 crystallizes in the primitive orthorhombic crystal symmetry having space group Pmn2 1 with lattice parameters a = 6.879 Å, b = 5.479 Å, c = 8.858 Å, V= 333.9 Å 3 and Z = 2, whereas AA16 crystallizes in the Pmna space group with lattice constants a = 8.93283 Å, b = 3.80848 Å, c = 8.6614 Å, V= 294.453 Å 3 and Z = 4; consequently, TMAA is 15% loosely packed compared to AA. While HZA 20 crystallizes in the primitive monoclinic structure having space group P2 1 /b with a = 5.663 Å, b = 12.436 Å, c = 5.506 Å, γ = 114.0 • , and Z = 4.…”

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Structural, vibrational and bonding properties of hydro-nitrogen solids under high pressure: An ab-initio study

2016

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Hydro-nitrogen solids are potential high energy density materials (HEDMs) due to high mass ratio of nitrogen which find wide range of applications as propellants and explosives. In the present work, we report the structural and vibrational properties of Tetramethyl Ammonium Azide (TMAA) and HydroZonium Azide (HZA) using density functional theory calculations by treating weak intermolecular interactions. The obtained ground state parameters using vdW-TS method are in good agreement with the experimental data. The pressure dependent lattice constants, compressibility and equation of state are discussed. The obtained equilibrium bulk moduli show the soft nature of these materials. The compressibility curves reveal that these compounds are highly compressible along crystallographic a-axis. We have also calculated the zone-center phonon frequencies and made a complete analysis of vibrational spectra at ambient as well as at high pressure. Contraction and elongation of C-H and N-H (NH 3 stretching) bonds under pressure lead to blue-and red-shift of the frequencies in the mid-IR region for TMAA and HZA compounds, respectively.

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“…7 Furthermore, coordination complexes contains ligand and various supramolecular interactions, such as hydrogen bonds, CH … π or π … π stacking, Van der Waals contacts or a combination of these, that intensively affect the properties of substance under high pressure. [8][9][10][11] Previous high pressure studies on the coordination complexes have found various phenomena, including piezochromism, isomerizations, and spin crossover effect. [12][13][14] However, few high pressure studies of energetic coordination complexes have been reported, and high pressure studies of energetic coordination complexes have other problems that we need to solve as follows: (1) the behavior of energetic ligands under pressure; (2) the relationship between flexible structures and pressure.…”

Section: Introductionmentioning

confidence: 99%

High pressure studies of Ni₃[(C₂H₅N₅)₆(H₂O)₆](NO₃)₆·1.5H₂O by Raman scattering, IR absorption, and synchrotron X-ray diffraction

et al. 2016

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Here we report the high-pressure studies of Ni 3 [(C 2 H 5 N 5 ) 6 (H 2 O) 6 ](NO 3 ) 6 ·1.5H 2 O (1) by in situ Raman scattering, infrared absorption, and synchrotron angle-dispersive X-ray diffraction techniques up to ~22 GPa at room temperature. We assign all the vibration modes of 1 at ambient conditions. Detailed spectroscopy analyses reveal a chemical transformation at ~0.75 GPa and a phase transition at ~4.7 GPa, which are related to the behaviors of energetic ligands and flexible structures. Upon compression, the distortion of energetic ligand induced the disconnection of NH 2 and triazole ring at 0.75 GPa. Further analyses of the N-H vibration modes indicate the phase transition at 4.7 GPa accompanied with the rearrangement of hydrogen bonds. Additionally, the lattice structure abnormally expanded above 8.6 GPa due to the deformation of nitrate ions and the extension of triazole ring. This work helps to understand the properties and the behaviors of energetic coordination complexes under high pressure.

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High pressure synchrotron x-ray diffraction and Raman scattering studies of ammonium azide

Abstract: Pressure-driven variations of hydrogen bonding energy in ammonium azide (NH4N3): IR absorption and Raman scattering studies

Cited by 23 publications

References 32 publications

Phase stability and lattice dynamics of ammonium azide under hydrostatic compression

Phase stability and lattice dynamics of ammonium azide under hydrostatic compression

Structural, vibrational and bonding properties of hydro-nitrogen solids under high pressure: An ab-initio study

High pressure studies of Ni₃[(C₂H₅N₅)₆(H₂O)₆](NO₃)₆·1.5H₂O by Raman scattering, IR absorption, and synchrotron X-ray diffraction

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High pressure synchrotron x-ray diffraction and Raman scattering studies of ammonium azide

Abstract: Pressure-driven variations of hydrogen bonding energy in ammonium azide (NH4N3): IR absorption and Raman scattering studies

Cited by 23 publications

References 32 publications

Phase stability and lattice dynamics of ammonium azide under hydrostatic compression

Phase stability and lattice dynamics of ammonium azide under hydrostatic compression

Structural, vibrational and bonding properties of hydro-nitrogen solids under high pressure: An ab-initio study

High pressure studies of Ni3[(C2H5N5)6(H2O)6](NO3)6·1.5H2O by Raman scattering, IR absorption, and synchrotron X-ray diffraction

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High pressure studies of Ni₃[(C₂H₅N₅)₆(H₂O)₆](NO₃)₆·1.5H₂O by Raman scattering, IR absorption, and synchrotron X-ray diffraction