Low-temperature structural phase transition in deuterated and protonated lithium acetate dihydrate

Schröder, Florian; Winkler, Bjoern; Haussühl, Eiken; Cong, P. T.; Wolf, B.; Avalos-Borja, M.; Quilichini, M.; Hennion, B.

doi:10.1016/j.jct.2010.03.006

Cited by 3 publications

(10 citation statements)

References 15 publications

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“…The excess entropy DS of the heat capacity anomaly in LiAc-CD 3 is %0:5R ln 2 ¼ 2:88 J Á mol 1 Á K 1 [4]. This is consistent with the assumption of having an order-disorder phase transition involving coupled pairs of methyl groups [4].…”

Section: Tablesupporting

confidence: 81%

“…The authors of that study thought that a similar ordering process in LiAc-CH 3 was unlikely to occur. In an earlier study, we have shown that the same transition occurs in fully protonated LiAc [4] and here we discuss the evidence for the occurrence of the transition in partially methyl-deuterated LiAc.…”

Section: Discussionmentioning

confidence: 51%

“…The temperature dependence of the heat capacity of LiAc-CH 2 D shows two excess peaks below 20 K, one at %14.5 K and one at %5.5 K. The maximum at %14.5 K is intermediate between the two maxima found in LiAc-CH 3 ð% 12 KÞ and LiAc-CD 3 ð% 17:5 KÞ [4]. For the peak at %5.5 K no equivalent peaks are observable in either LiAc-CH 3 or LiAc-CD 3 .…”

Section: Resultsmentioning

confidence: 86%

“…The crystal growth is described elsewhere and more details on the structure of this crystal can be obtained there as well [4]. Single crystals of partially methyl-deuterated lithium acetate dihydrate (LiAc-CH 2 D) were provided by H. Zimmermann, Max-Planck-Institut für medizinische Forschung, Heidelberg.…”

Section: Samplesmentioning

confidence: 99%

“…At low temperatures the structure is fully ordered [1][2][3]. Recently, we have explored the low-temperature thermodynamic and elastic properties of protonated and deuterated lithium acetate dihydrate [4,5]. The isotopic exchange of hydrogen atoms by deuterium atoms leads to a significant change of the thermal expansion coefficients and the temperature of the transition from the dynamically disordered high temperature phase to the ordered low temperature phase increases by %5.5 K. The present study complements these earlier findings in that here we study the temperature dependence of the heat capacity of methyl-monodeuterated lithium acetate dihydrate, LiAc-CH 2 D. In addition, we present Raman spectra of LiAc-CH 2 D at ambient pressure to explore the effect of isotopic exchange on the lattice dynamics.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Evidence for low-temperature isotopic ordering in methyl-monodeuterated lithium acetate dihydrate

Schröder

Winkler

Bauer

et al. 2012

The Journal of Chemical Thermodynamics

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Section: Tablesupporting

confidence: 81%

Section: Discussionmentioning

confidence: 51%

Section: Resultsmentioning

confidence: 86%

Section: Samplesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Evidence for low-temperature isotopic ordering in methyl-monodeuterated lithium acetate dihydrate

Schröder

Winkler

Bauer

et al. 2012

The Journal of Chemical Thermodynamics

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Elastic Properties, Thermal Expansion, and Polymorphism of Acetylsalicylic Acid

Bauer

Haussühl

Winkler

et al. 2010

Crystal Growth & Design

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High quality single crystals of acetylsalicylic acid (aspirin) with dimensions up to about 30 cm 3 were grown from saturated solutions. The complete elastic stiffness tensor was determined by two different ultrasonic techniques. The thermal expansion coefficients were measured by dilatometry. The thermal expansion is anisotropic, with a minimum of the longitudinal effect parallel to the direction [010]. The expansion perpendicular to this direction is larger by a factor of 2. The anisotropy of the longitudinal elastic stiffness is less pronounced; the difference between the minimum and maximum values is approximately 30%. The maximum elastic stiffness is observed along the directions of the hydrogen bonds linking the centrosymmetric acetylsalicylic acid dimers. The experimentally determined elastic stiffness coefficients and the observed morphology have been compared to results from atomistic model calculations. This comparison allows us to assess the reliability of predictions made with respect to a potential polymorph.

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Influence of deuteration on lithium acetate dihydrate studied by inelastic X-ray scattering, density functional theory, thermal expansion, elastic and thermodynamic measurements

et al. 2011

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The influence of deuteration on the properties of lithium acetate dihydrate has been investigated by thermal expansion measurements, ultrasound spectroscopy and calorimetry. Inelastic X-ray scattering has been employed to investigate if the low temperature structural phase transition can be detected by a change in the vibrational spectrum. Density functional theory, DFT, calculations have been employed to complement the experimental investigations. The thermal expansion coefficients and the specific heat of the deuterated compound differ significantly from the protonated form. The differences in the elastic stiffness coefficients are just above the detection limit of the technique employed here. Temperature dependent inelastic X-ray spectroscopic measurements show no significant change of the vibrational spectrum when crossing the transition temperature. The DFT calculations show that the methyl group dynamics are best described in the framework of coupled rotators of opposing methyl groups. One of the coupled rotational modes corresponds to a hindered rotator with a barrier of 15 meV, while the other is a free rotator.

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Low-temperature structural phase transition in deuterated and protonated lithium acetate dihydrate

Cited by 3 publications

References 15 publications

Evidence for low-temperature isotopic ordering in methyl-monodeuterated lithium acetate dihydrate

Evidence for low-temperature isotopic ordering in methyl-monodeuterated lithium acetate dihydrate

Elastic Properties, Thermal Expansion, and Polymorphism of Acetylsalicylic Acid

Influence of deuteration on lithium acetate dihydrate studied by inelastic X-ray scattering, density functional theory, thermal expansion, elastic and thermodynamic measurements

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