Disorder in solid CBr2Cl2 and CBrCl3

Lee-Dadswell, S. E.; Torrie, B. H.; Binbrek, O. S.; Powell, B. M.

doi:10.1016/s0921-4526(97)00619-4

Cited by 7 publications

(10 citation statements)

References 5 publications

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“…The former technique allows the measurement of the dynamic response within a broad time scale but it is insensitive to fine details of molecular motions, whereas the latter has a restricted time window but monitors the movement of individual chlorine atoms. Results derived from the concurrent use of NQR and molecular simulations show that large-angle rotations of tetrahedral about their higher symmetry axes (CBrCl 3 , and CBr 2 Cl 2 with C 3v and C 2v point-group symmetries, respectively) lead to a statistical occupancy of 75% for Cl and 25% for Br atoms in the case of CBrCl 3 , and 50% for Cl and 50% for Br atoms for CBr 2 Cl 2 in agreement with X-ray and neutron diffraction measurements 20,21,29,30 . These experimental techniques also show that the relaxation movements arise from different dynamics exhibited by molecules in the asymmetric unit of the crystalline lattice that are non-equivalent with respect to their molecular environment.…”

Section: Introductionsupporting

confidence: 71%

Dynamic heterogeneity in an orientational glass

Caballero

Zuriaga

Tamarit³

et al. 2017

The Journal of Chemical Physics

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Family of compounds CBr n Cl 4−n has been proven helpful in unraveling microscopic mechanisms responsible of glassy behavior. Some of the family members show translational ordered phases with minimal disorder which appears to reveal glassy features, thus deserving special attention in the search for universal glass anomalies. In this work, we studied CBrCl 3 dynamics by performing extensive molecular dynamics simulations. Molecules of this compound perform reorientational discrete jumps, where the atoms exchange equivalent positions among each other revealing a cage-orientational jump motion fully comparable to the cage-rototranslational jump motion in supercooled liquids. Correlation times were calculated from rotational autocorrelation functions showing good agreement with previous reported dielectric results. From mean waiting and persistence times calculated directly from trajectory results, we are able to explain which microscopic mechanisms lead to characteristic times associated with α and β-relaxation times measured experimentally. We found that two nonequivalent groups of molecules have a longer characteristic time than the other two nonequivalent groups, both of them belonging to the asymmetric unit of the monoclinic (C2/c) lattice.

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Section: Introductionsupporting

confidence: 71%

Dynamic heterogeneity in an orientational glass

Caballero

Zuriaga

Tamarit³

et al. 2017

The Journal of Chemical Physics

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“…In this special phase the molecular centres are located in a highsymmetry lattice (face centered cubic, body centered cubic or rhombohedral), but the molecules can rotate around their equilibrium position. The three characteristic phases (ordered, plastic crystalline and liquid) have been studied extensively for each halomethane mentioned above [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Comparison of the atomic level structure of the plastic crystalline and liquid phases of CBr₂Cl₂: neutron diffraction and reverse Monte Carlo modelling

Pothoczki¹,

Temleitner²,

Pardo³

et al. 2013

J. Phys.: Condens. Matter

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Abstract. Neutron diffraction results obtained for plastic crystalline dichlorodibromomethane (CBr 2 Cl 2 ) have been modelled by means of the Reverse Monte Carlo method. Comparison with its liquid phase is provided at several levels of the atomic structure (total scattering structure factors, partial radial distribution functions, orientational and dipole-dipole correlations). Results reveal that the relative orientation of neighbouring molecules largely depends on the steric effect. The small dipole moment has not as strong influence as the steric effect on the short range order. Our observations fit well with earlier findings presented for the series CBr n Cl 4-n (n=0, 1, 2, 4).

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“…14 As for CBr 2 Cl 2 the polymorphism at ordinary pressure consists of two stable forms in the solid state. 16,23 At ca. 259 K, the low-temperature phase transforms to an OD face centred-cubic (FCC) phase, stable up to the melting point (294 K).…”

Section: Introductionmentioning

confidence: 99%

Polymorphism of CBr₂Cl₂

et al. 2008

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The polymorphism of dibromodichloromehtane (CBr 2 Cl 2 ) has been studied by means of a wide set of experimental techniques as a function of temperature and pressure. From the p-V-T diagram and the derived p-T diagram the volume variations at the transition points have been calculated and compared with those obtained by means of X-ray and neutron powder diffraction. By combining the experimental techniques, it has been demonstrated the existence of a highpressure orientationally disordered rhombohedral phase (a R E 14.6 AE 0.3 A ˚and a E 89.2 AE 0.21). The existence of a glass transition within the monoclinic (C2/c, Z = 32) low-temperature ordered phase associated with the freezing of exchange positions between Cl and Br atoms is analyzed considering the asymmetry of the intermolecular interactions by means of the study of the thermal expansion tensor. The change of the derivative of the aspherism index, previously reported as a possible ''fingerprint'' for this kind of glass transitions, is found.

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Disorder in solid CBr2Cl2 and CBrCl3

Cited by 7 publications

References 5 publications

Dynamic heterogeneity in an orientational glass

Dynamic heterogeneity in an orientational glass

Comparison of the atomic level structure of the plastic crystalline and liquid phases of CBr₂Cl₂: neutron diffraction and reverse Monte Carlo modelling

Polymorphism of CBr₂Cl₂

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Disorder in solid CBr2Cl2 and CBrCl3

Cited by 7 publications

References 5 publications

Dynamic heterogeneity in an orientational glass

Dynamic heterogeneity in an orientational glass

Comparison of the atomic level structure of the plastic crystalline and liquid phases of CBr2Cl2: neutron diffraction and reverse Monte Carlo modelling

Polymorphism of CBr2Cl2

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Product

Resources

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Comparison of the atomic level structure of the plastic crystalline and liquid phases of CBr₂Cl₂: neutron diffraction and reverse Monte Carlo modelling

Polymorphism of CBr₂Cl₂