Structure of the fourth form of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (γ-HMX), 2C4H8N8O8.0.5H2O

Main, P. C.; Cobbledick, R. E.; Small, R. W. H.

doi:10.1107/s0108270185007739

Cited by 127 publications

(102 citation statements)

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“…More than twenty peaks can be easily assigned for the P2 1 /c monoclinic structure of ␤-HMX, and the agreement between the measured and calculated diffraction patterns is very good. Refined cell parameters of ␤-HMX at 0.2 GPa are aϭ6.495(Ϯ0.014) Å, bϭ10.952(Ϯ0.010) Å, cϭ8.693 (Ϯ0.024) Å, ␤ϭ124.53°͑Ϯ0.20͒ with ϭ1.931 g/cm 3 . This structure is consistent with that of ␤-HMX: a 0 ϭ6.54 Å, b 0 ϭ11.05 Å, c 0 ϭ8.70 Å, ␤ϭ124.30°, ϭ1.893 g/cm 3 at ambient conditions.…”

Section: Methodsmentioning

confidence: 99%

“…2 The ␥ phase was later found to be a hydrated form of HMX. 3 The stabilities of these polymorphs are known to be ␤Ͼ␣Ͼ␥Ͼ␦ at ambient conditions. 4 Although the stability field of these phases at high pressures and temperatures are not very well known, the ␤ phase is considered the most stable phase at high pressures at least to 10 GPa.…”

Section: Introductionmentioning

confidence: 99%

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Equation of state, phase transition, decomposition of β-HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) at high pressures

Yoo

Cynn

1999

The Journal of Chemical Physics

188

186

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Equation of state, phase transition, decomposition of β-HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) at high pressures

Yoo

Cynn

1999

The Journal of Chemical Physics

188

186

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“…HMX is one of a number of commonly used energetic materials and is a common constituent of plastic bonded explosives; in a similar manner to materials such as RDX and PETN. HMX occurs in four polymorphic forms, α, β, δ and ε [1-6] (and also a hydrated form, termed γ [7]), of these the most stable thermodynamically is β-HMX. This form is monoclinic, space group P2 1 /n, a 0 = 6.526 Å, b 0 = 11.037 Å, c 0 = 7.364 Å, β = 102.66°.…”

Section: Introductionmentioning

confidence: 99%

Growth and dislocation studies of β-HMX

Gallagher

Sherwood

Vrcelj

2014

Chemistry Central Journal

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BackgroundThe defect structure of organic materials is important as it plays a major role in their crystal growth properties. It also can play a subcritical role in “hot-spot” detonation processes of energetics and one such energetic is cyclotetramethylene-tetranitramine, in the commonly used beta form (β-HMX).ResultsThe as-grown crystals grown by evaporation from acetone show prismatic, tabular and columnar habits, all with {011}, {110}, (010) and (101) faces. Etching on (010) surfaces revealed three different types of etch pits, two of which could be identified with either pure screw or pure edge dislocations, the third is shown to be an artifact of the twinning process that this material undergoes. Examination of the {011} and {110} surfaces show only one type of etch pit on each surface; however their natural asymmetry precludes the easy identification of their Burgers vector or dislocation type. Etching of cleaved {011} surfaces demonstrates that the etch pits can be associated with line dislocations. All dislocations appear randomly on the crystal surfaces and do not form alignments characteristic of mechanical deformation by dislocation slip.ConclusionsCrystals of β-HMX grown from acetone show good morphological agreement with that predicted by modelling, with three distinct crystal habits observed depending upon the supersaturation of the growth solution. Prismatic habit was favoured at low supersaturation, while tabular and columnar crystals were predominant at higher super saturations. The twin plane in β-HMX was identified as a (101) reflection plane. The low plasticity of β-HMX is shown by the lack of etch pit alignments corresponding to mechanically induced dislocation arrays. On untwinned {010} faces, two types of dislocations exist, pure edge dislocations with b = [010] and pure screw dislocations with b = [010]. On twinned (010) faces, a third dislocation type exists and it is proposed that these pits are associated with pure screw dislocations with b = [010].Graphical abstractEtch pits on the twinned (010) face of β-HMX.

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“…The PT γ → β is accompanied by loss of structural water (see [40]). As was shown in [41], a solid-solid structural transformation, initiated by the release of a volatile impurity (e.g.…”

Section: The Role Of Mechanical Effects On Pts Of Molecular Crystalsmentioning

confidence: 99%

Kinetics of Polymorphic Transitions in Energetic Compounds

Чуканов¹,

Захаров²,

Korsunskiy³

et al. 2016

Cent. Eur. J. Energ. Mater.

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Available data on the kinetics of polymorphic transitions (PTs) in energetic compounds under isothermal conditions are summarized and discussed. It is shown that the general kinetic regularities of these processes (stepwise and continuous regimes) depend on their topotactic mode (frontal or quasihomogeneous, respectively). In reverse PTs, a nucleation stage is not observed, which is explained by the presence of nuclei of the low-temperature polymorph in the preheated sample. The influence of mechanical effects on the kinetics of PTs in molecular crystals is discussed.

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Structure of the fourth form of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (γ-HMX), 2C4H8N8O8.0.5H2O

Cited by 127 publications

References 1 publication

Equation of state, phase transition, decomposition of β-HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) at high pressures

Equation of state, phase transition, decomposition of β-HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) at high pressures

Growth and dislocation studies of β-HMX

Kinetics of Polymorphic Transitions in Energetic Compounds

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