Vibrational Spectrum of Barium Azide Single Crystals

Iqbal, Zafar; Brown, Chris W.; Mitra, S. S.

doi:10.1063/1.1673724

Cited by 17 publications

(5 citation statements)

References 5 publications

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“…Thus, the magnitude of Ω (2) is necessarily zero, given no doorway modes are present. The calculated Γ-point Ω max of Ba(N 3 ) 2 agrees well with experimental measurements (230–240 cm –1 ) and suggests minimal error in our selection of the phonon bath for this material.…”

Section: Resultssupporting

confidence: 81%

A Pathway to the Athermal Impact Initiation of Energetic Azides

et al. 2018

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Energetic materials (explosives, propellants, and pyrotechnics) are used in a broad range of public and private sector applications. The design of novel, safe materials is therefore of critical importance. At present, physical mechanisms able to rationalize the impact sensitivity properties of energetic materials remain limited. Investigation therefore has required lengthy synthesis and experimental testing. On the basis of knowledge of the effects of mechanical impact, an ab initio model is developed to rationalize and describe the impact sensitivity of a series of crystalline energetic azide materials. It is found that electronic excitation of the azido anion is sufficient to permit bond rupture and therefore offers a plausible mechanism for initiation of these materials. The athermal excitation can be achieved through consideration of nonadiabatic vibronic processes. Across the series of azides studied here, the electronic structure of the azido anion is found to remain largely constant. By considering only the relative rates of vibrational energy transfer within the crystalline materials, it is found that a direct correlation exists between the relative impact sensitivity and the rate of energy up-conversion. Thus, the present contribution demonstrates a fully ab initio method to describe the athermal initiation of ideal, crystalline energetic materials and predict their relative sensitivity. Without the need for any experimental input beyond a crystal structure, this method therefore offers a means to selectively design novel materials for targeted application.

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Section: Resultssupporting

confidence: 81%

A Pathway to the Athermal Impact Initiation of Energetic Azides

et al. 2018

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“…Therefore, we assigned this mode to NNN symmetric stretch mode. The fundamental ν 1 symmetric stretch vibrations are IR inactive in azides with linear symmetric azide ions, ,,, while they become IR active for these azides possess nonlinear or/and asymmetric azide ions. − Therefore, we infer that the azide ions become nonlinear and/or asymmetric starting from 11.7 GPa. This phenomenon was also found in IR study of RbN 3 …”

Section: Resultsmentioning

confidence: 90%

High-Pressure Raman and Infrared Spectroscopic Studies of Cesium Azide

Zhu

Jiang

et al. 2016

J. Phys. Chem. C

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In this work, we present the effects of high pressure on the structure and stability of cesium azide (CsN 3 ) with the pressure up to ∼30.0 GPa, as studied by Raman and IR spectroscopy. Three phase transitions of Phase II → III → IV → V were revealed at ∼0.5, ∼3.7, and ∼16.0 GPa. The abnormal softening behavior of T(E g ) mode reveals the shearing distortion during Phase II → III transition. Moreover, changes of lattice modes and splitting of the degenerate T(E g ) and R(E g ) modes in Phase III indicate the breaking of crystallographically equivalent condition of azide ions. Phase IV was found to possess the C2/m structure, and Phase V has a lower symmetry structure than other phases. The IR measurements show the evolution of the NNN bending modes and the IR-active behavior of the symmetric stretch ν 1 mode under pressure, which collectively reveal the rotation and bending of the azide ions upon compression. The azide ions groups were found to further bend under pressure, and the bent azide ions might enhance propensity of nitrogen polymerization.

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“…The mode with weak intensity at 1374 cm –1 is assigned to the NNN symmetric stretch mode, labeled as ν sy temporarily, corresponding to the ν 1 ( A 1 g ) mode at 1375 cm –1 (11.9 GPa) in the Raman spectra. The ν sy mode presented as IR-active at this pressure due to the NNN becoming nonlinear/asymmetric upon compression, as is the fact in Ca(N 3 ) 2 , Ba(N 3 ) 2 , and Pb(N 3 ) 2 . − In the process of 10.8–14.9 GPa, the relative intensity of C I4 and C I5 is gradually changed accompanied by the overlap and cross of the ν 2 ( A 2 u ) and ν′ 2 ( E u ) modes, indicating the process of the phase transition (γ → δ). Further compression to 16.1 GPa resulted in the disappearance of C I2 and C I3 modes accompanied by the merging of C I4 and C I5 (Figure f).…”

Section: Results and Discussionmentioning

confidence: 81%

High-Pressure Studies of Rubidium Azide by Raman and Infrared Spectroscopies

et al. 2015

J. Phys. Chem. C

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We report the high-pressure studies of RbN 3 by Raman and IR spectral measurements at room temperature with the pressure up to 28.5 GPa and 30.2 GPa, respectively. All the fundamental vibrational modes were resolved by combination of experiment and calculation. Detailed spectroscopic analyses reveal two phase transitions at ~ 6.5 and ~16.0 GPa, respectively. Upon compression, the shearing distortion of the unit cell induced the displacive structural transition of phase α → γ.Further analyses of the mid-IR spectra indicate the evolution of N 3 − with the arrangement sequence of orthogonal → parallel → orthogonal during the phase transition of phase α → γ → δ. Additionally, the pressure-induced non-linear/asymmetric existence of N=N=N and the two crystallographically nonequivalent sites of N 3 − were observed in phase δ.

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Vibrational Spectrum of Barium Azide Single Crystals

Cited by 17 publications

References 5 publications

A Pathway to the Athermal Impact Initiation of Energetic Azides

A Pathway to the Athermal Impact Initiation of Energetic Azides

High-Pressure Raman and Infrared Spectroscopic Studies of Cesium Azide

High-Pressure Studies of Rubidium Azide by Raman and Infrared Spectroscopies

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