Melting temperature and anharmonicity of lattice vibrations in solids

Сандитов, Б. Д.; Darmaev, M. V.; Сандитов, Д. С.; Mantatov, V. V.

doi:10.1134/s0036024408070339

Cited by 6 publications

(4 citation statements)

References 1 publication

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“…Such atoms, which are capable of critical displacements, are called delocalized atoms. According to the delocalized atom model [9,11,12,13], the elementary act of glass softening consists of the limiting elastic deformation of an interatomic or an intermolecular bond. According to that model, the elastic modulus is given by,…”

Section: Resultsmentioning

confidence: 99%

Temperature robustness of oscillation-type density meters

Schiebl¹,

Wasylewski²

2019

Meas. Sci. Technol.

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The temperature robustness of an oscillation-type density meter was investigated with the aim of examining the limitations of measurement uncertainty. We demonstrate that the measured density by such a device reveals a relaxational behavior after a temperature adjustment of the glass vibrating tube. From an analysis of the time-dependent measured density, we demonstrate that this behavior is neither caused by a time-dependent temperature of the oscillation tube due to convective heat transfer after temperature adjustment of the device, or by a time-dependent spring constant of the oscillation tube, since this effect is suppressed by a reference oscillation tube. Instead, we show that this behavior is inherently connected to the relaxational behavior of the volume of the tube which is governed by the elastic properties of glass. By rigorous analysis of the time characteristics of the measured density, we were able to determine the characteristic time constant of the relaxation at different temperatures, and consequently we further show that the characteristic time constant of the relaxation follows a temperature-activated behavior. A characteristic waiting time after a temperature adjustment of the device is also presented in order to keep the uncertainty as small as possible.

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Section: Resultsmentioning

confidence: 99%

Temperature robustness of oscillation-type density meters

Schiebl¹,

Wasylewski²

2019

Meas. Sci. Technol.

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“…In terms of the excited state model [4][5][6], the constancy of the parameter ratio (Eq. (2)) in the Bar tenev-Ritland equation arguably originates in the criterion for glass transition conditions (Eq.…”

Section: C ≈ ≈mentioning

confidence: 99%

“…In this work, we used both relaxation theory [1][2][3] and the excited state model [4][5][6] to provide a possible explanation for the observed constancy. According to the excited state model, the liquid-glass transition occurs when the average thermal energy of the oscilla tion of atoms in a crystal lattice (3kT) becomes equal to or less than the enthalpy of the ultimate elastic deformation of interatomic bonds (ΔH e ): 3kT ≤ ΔH e .…”

Section: C ≈ ≈mentioning

confidence: 99%

Cooling rate dependency of fluctuations in the melt volume of amorphous materials

Sangadiev

2012

Russ. J. Phys. Chem.

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It has been shown that the physical properties of any amorphous material in the glass transition region change in a similar manner. The cooling rate depen dence q = dT/dt of glass transition temperature T g can thus be described universally by the Bartenev-RitlandAs can be seen from the table, the ratio of the two vari ables in this formula has the same constant value for any glasslike material [2]:In this work, we used both relaxation theory [1-3] and the excited state model [4-6] to provide a possible explanation for the observed constancy. According to the excited state model, the liquid-glass transition occurs when the average thermal energy of the oscilla tion of atoms in a crystal lattice (3kT) becomes equal to or less than the enthalpy of the ultimate elastic deformation of interatomic bonds (ΔH e ): 3kT ≤ ΔH e .The ΔH e /kT g ratio remains ~3 at T = T g [5], con firming that the fraction of the fluctuation volume (f = ΔV e /V) formed by the displacement of structural units (an atom or group of atoms) from their equilibrium Abstract-Fluctuations in the melt volume of the amorphous materials as a function of cooling rate is estab lished. The observed dependency is similar to the one found for the glass transition temperature (the Bar tenev-Ritland equation). The constant ratio of the empirical parameters in the equation is explained in terms of the excited state model.

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“…The kinetic unit (an atom, a group of atoms) capable of such a critical shift, called as "excited atom," and the approach itself-the model of the excited state [1,2].…”

Section: Introductionmentioning

confidence: 99%