Monitoring the α→β solid–solid phase transition of RDX with Raman spectroscopy: A theoretical and experimental study

Infante-Castillo, Ricardo; Pacheco‐Londoño, Leonardo C.; Hernández‐Rivera, Samuel P.

doi:10.1016/j.molstruc.2010.02.021

Cited by 63 publications

(70 citation statements)

References 36 publications

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“…1a) has been widely studied both experimentally [38][39][40][41][42][43][44][45] and theoretically [35,[46][47][48][49][50][51][52]. There are four known polymorphs of RDX, denoted a [53], b [54], e [55], and c [56].…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulations of the Collapse of a Cylindrical Pore in the Energetic Material α-RDX

Eason

Sewell

2015

J. dynamic behavior mater.

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Molecular dynamics simulations were used to study the shock-induced collapse of cylindrical pores in oriented single crystals of the energetic material a-1,3,5-trinitroperhydro-1,3,5-triazine (a-RDX). The shock propagation direction was parallel to the [100] crystal direction and the cylinder axis of the initially 35.0 nm diameter pore was parallel to [010]. Features of the collapse were studied for Rankine-Hugoniot shock pressures P s = 9.71, 24.00, and 42.48 GPa. Pore collapse for the weak shock is dominated by visco-plastic deformation in which the pore pinches shut without jet formation and with little penetration of the upstream material into the downstream pore wall. For the strong shock the collapse is hydrodynamiclike and results in the formation of a jet that penetrates significantly into the downstream pore wall. Material flow during collapse was characterized by examining the spread and mixing of sets of initially contiguous molecules and evolution of local velocity fields. Local disorder during collapse was assessed using time autocorrelation functions for molecular rotation. Energy deposition and localization was studied using spatial maps of temperature and pressure calculated as functions of time.

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Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulations of the Collapse of a Cylindrical Pore in the Energetic Material α-RDX

Eason

Sewell

2015

J. dynamic behavior mater.

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“…8,9 On account of its high metastability with respect to the -form, it was only recently structurally characterized. 10 There has been a long-standing assumption that -RDX could only be grown from high boiling solvents, 7,8 but Infante-Castillo et al 11 demonstrated on the basis of Raman spectra that -RDX can undergo a solid-solid phase transition to -RDX upon heating. Furthermore, Goldberg et al…”

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confidence: 99%

Experimental and DFT-D Studies of the Molecular Organic Energetic Material RDX

et al. 2013

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EPSRC's High End Computing Programme. We acknowledge the support of the Diamond Light Source, STFC, and the ISIS Neutron and Muon Facility. Supporting information:The remaining DSC thermograms for β-RDX (Figures S1−S4); a comparison between the calculated lattice parameters and unit cell volumes for α-and γ-RDX, compared to previous DFT-D studies as well as relevant experimental data ( Figures S5 and S6); comparison of predicted INS spectra for α-RDX to those for γ-and ε-RDX at similar pressures ( Figures S7 and S8); a comparison of the DFT-D predicted crystallographic parameters with corresponding experimental data for α-, γ-, and ε-RDX (Tables S1, S3, and S4, respectively); full lists of calculated phonon modes as a function of pressure for α-, γ-, and ε-RDX compared to experimental Raman data, including pressure-induced shift values (Tables S2, S5, and S6). This material is available free of charge via the Internet at http://pubs.acs.org Graphical abstract: Abstract:We have performed simulations utilizing the dispersion-corrected density functional theory method (DFT-D) as parametrized by Grimme on selected polymorphs of RDX (cyclotrimethylenetrinitramine). Additionally, we present the first experimental determination of the enthalpy of fusion (ΔH fus ) of the highly metastable β-form of RDX. The characteristics of fusion for β-RDX were determined to be 186.7 ± 0.8 °C, 188.5 ± 0.4 °C, and 12.63 ± 0.28 kJ mol -1 for the onset temperature, peak temperature (or melting point), and ΔH fus , respectively. The difference in experimental ΔH fus for the α-and β-forms of RDX is 20.46 ± 0.92 kJ mol -1 . Ambient-pressure lattice energies (E L ) of the α-and β-forms of RDX have been calculated and are in excellent agreement with experiment. In addition the computationally predicted difference in E L (20.35 kJ mol -1 ) between the α-and β-forms is in excellent agreement with the experimental difference in ΔH fus . The response of the lattice parameters and unit-cell volumes to pressure for the α-and γ-forms have been investigated, in addition to the first high-pressure computational study of the ε-form of RDX-these results are in very good agreement with experimental data. Phonon calculations provide good agreement for vibrational frequencies obtained from Raman spectroscopy, and a predicted inelastic neutron scattering (INS) spectrum of α-RDX shows excellent agreement with experimental INS data determined in this study. The transition energies and intensities are reproduced, confirming that both the eigenvalues and the eigenvectors of the vibrations are correctly described by the DFT-D method. The results of the high-pressure phonon calculations have been used to show that the heat capacities of the α-, γ-, and ε-forms of RDX are only weakly affected by pressure. 4

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“…Acquisitions were performed with 20 scans, an exposure time of 10 s per scan and a resolution of 1 cm . The bands observed were attributed to vibration modes according to information found in the literature [6,7,15,16]. To designate vibrational modes, the following abbreviations are used: ν for stretching vibrations and δ for scissoring deformations.…”

Section: Raman Spectroscopymentioning

confidence: 99%

“…In particular, Raman spectroscopy has provided insights for both the identification and the characterization of energetic materials [4][5][6][7]. Due to fewer overlaps in Raman spectra compared to the corresponding data obtained by infrared absorption, this technique is well suited for the analysis of complex energetic formulations.…”

Section: Introductionmentioning

confidence: 99%

Plasticization of Submicron-Structured LOVA Propellants by a Linear Dinitramine

Brize¹,

Spitzer²

2016

Cent. Eur. J. Energ. Mater.

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Raman spectroscopy is a powerful tool for the analysis of complex energetic materials. In this work, this technique has been used to observe the inter-molecular interactions occurring in nitrocellulose-based propellants containing 1,3,5-trinitro-1,3,5-triazinane (RDX) and plasticized with 2,4-dinitro-2,4-diazahexane (DNDA6). The plasticization mechanism of nitrocellulose by DNDA6 was observed. RDX was found to be markedly uninvolved in chemical interactions in these matrices, hinting at a potential loss of stability in compositions for LOVA (LOw Vulnerability Ammunitions).

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Monitoring the α→β solid–solid phase transition of RDX with Raman spectroscopy: A theoretical and experimental study

Cited by 63 publications

References 36 publications

Molecular Dynamics Simulations of the Collapse of a Cylindrical Pore in the Energetic Material α-RDX

Molecular Dynamics Simulations of the Collapse of a Cylindrical Pore in the Energetic Material α-RDX

Experimental and DFT-D Studies of the Molecular Organic Energetic Material RDX

Plasticization of Submicron-Structured LOVA Propellants by a Linear Dinitramine

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