Effect of isotopic composition on phonon modes. Static atomic displacements in crystals

Zhernov, A. P.; Inyushkin, A. V.

doi:10.3367/ufnr.0171.200108b.0827

Cited by 19 publications

(19 citation statements)

References 113 publications

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“…This is why the lattice parameter may depend on the isotopic composition of a crystal. Theoretically, this effect can be assessed with ab initio approaches, which employ the parameters of the potentials acting on crystal atoms [8][9]. No calculations of this kind have been completed successfully so far, except for semiconductors with simple lattices.…”

Section: Theorymentioning

confidence: 99%

Effect of the isotopic composition on the lattice parameter of boron

Chkhartishvili¹,

Gabuniya²,

Tsagareishvili³

2008

Powder Metall Met Ceram

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It is shown that the lattice parameter may be expected to change upon substitution of heavier isotopes by lighter ones in crystalline modifications of boron and their solid solutions and compounds. This isotopic effect is estimated using the diatomic model and semiclassical B-B interatomic interaction potential. The maximum percent change in the lattice parameter after substitution of all 11 B atoms by 10 B atoms is estimated at 0.42%. This value is of the same order of magnitude as the isotopic changes in the lattice parameter measured in boron carbides.

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Section: Theorymentioning

confidence: 99%

Effect of the isotopic composition on the lattice parameter of boron

Chkhartishvili¹,

Gabuniya²,

Tsagareishvili³

2008

Powder Metall Met Ceram

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“…Therefore, in what follows we shall only consider the intervals of temperatures and wave vectors q when this inequality is fulfilled. In this case, the dominant contribution to the volume absorption of acoustic waves is due to the scattering by defects, including the isotopic scattering, and normal processes of the phonon-phonon scattering (see, e.g., [1,10]). We shall restrict ourselves to the consideration of these relaxation processes while analyzing the absorption of the long-wave transverse ultrasound (ћω…”

Section: Scattering On Defects and Anharmonic Scattering Processesmentioning

confidence: 99%

“…We shall restrict ourselves to their consideration in this paper. The isotropic medium approximation [4][5][6][8][9][10][11], which is commonly used to estimate the probability of various scattering processes, is inadequate for germanium, silicon, diamond and other semiconductor crystals having the cubic symmetry and a considerable anisotropy both of the second-and third-order elasticity moduli. The anisotropic continuum model provides a convenient solution to these problems.…”

Section: Introductionmentioning

confidence: 99%

“…The absorption equals 0.67, 0.87 and 0.93 in KCl, NaCl and GaAs, respectively. In the case of the anharmonic scattering processes, the absorption reaches its maximum , but also by those proportional to the moduli and (see formula (10)). Therefore, in crystallographic directions like [101] and [111] such compensation is not realized in the matrix element of the three-phonon scattering processes (see Table 1) and, because of the coefficient BB 0 , the ultrasound absorption in these directions in KCl and NaCl is two orders of magnitude higher than in Ge.…”

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confidence: 99%

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Relaxation of quasi-transverse phonons in the Herring mechanism and ultrasound absorption in cubic crystals with positive and negative anisotropies of the second-order elastic moduli

Kuleyev

2009

Phys. Solid State

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The transverse ultrasound absorption in cubic crystals with positive and negative anisotropies of the second-order elasticity moduli is analyzed. The scattering of the ultrasound by defects and during anharmonic scattering processes is considered. The transverse ultrasound absorption is analyzed as a function of the wave-vector direction in terms of the anisotropic continuum model. The Landau-Rumer mechanism is considered for anharmonic scattering processes. Known values of the second-and thirdorder elasticity moduli are used to calculate parameters determining the ultrasound absorption. It is shown that the angular dependences of the transverse ultrasound absorption differ qualitatively if the anharmonic scattering processes dominate in cubic crystals with positive and negative anisotropies of the second-order elasticity moduli.For the scattering by defects and the anharmonic scattering processes, the angular dependences of the transverse ultrasound absorption exhibit the inverse behavior, making it possible to determine the dominating mechanism of the ultrasound relaxation in the crystals under study.

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“…A successful development of a new line in applied physics, viz., isotope engineering of materials, has made possible the production of isotopically enriched chemical elements in reasonable amounts [1]. This has caused particular attention to investigating their physical properties [2][3][4][5]. Generally, the isotope (mass) effects in crystals are divided into two types of manifestation.…”

Section: Introductionmentioning

confidence: 99%

Longitudinal Ultrasound Velocity and Attenuation in Isotopically Enriched Cadmium

Булатов¹,

Ковтун²,

Klochko³

et al. 2018

Metallofiz. Noveishie Tekhnol.

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The results of the acoustic-properties' study of high-purity (> 99.999%) cadmium enriched to 66.4% with the isotope 106 Cd and to 82.2% with the isotope 116 Cd are presented for the temperature range of 77-300 K. Isotopic effects are observed in the temperature dependence of the 50 MHz ultrasound propagation velocity and attenuation. A comparison of the sound velocity data for the 106 Cd and 116 Cd samples has revealed a first-order isotopic effect with a characteristic linear dependence on the isotopes' masses difference, and it determines the phonon-spectrum change caused by the isotope composition. Measuring the attenuation of the longitudinal ultrasound made it possible to detect a second-order isotopic effect with a quadratic dependence on the isotopes' masses difference. The quadratic effect is due to a disordered isotope distribution, and it causes an additional relaxation mechanism for phonon scattering.Key words: natural cadmium, 106 Cd and 116 Cd isotopes, isotopic disorder, velocity and attenuation of longitudinal ultrasound.Представлено результати дослідження акустичних властивостей високочистого (> 99,999%) кадмію, збагаченого до 66,4% ізотопом 106 Cd і до 82,2% ізотопом 116 Сd, у температурній області 77-300 К. Ізотопічні ефекти спостерігалися на температурній залежності швидкости поширення та згасання ультразвуку частотою у 50 МГц. Порівняння даних для швидкости звуку зразків 106 Cd і 116 Сd виявляє ізотопічний ефект першого порядку Corresponding author: A. S. Bulatov

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Effect of isotopic composition on phonon modes. Static atomic displacements in crystals

Cited by 19 publications

References 113 publications

Effect of the isotopic composition on the lattice parameter of boron

Effect of the isotopic composition on the lattice parameter of boron

Relaxation of quasi-transverse phonons in the Herring mechanism and ultrasound absorption in cubic crystals with positive and negative anisotropies of the second-order elastic moduli

Longitudinal Ultrasound Velocity and Attenuation in Isotopically Enriched Cadmium

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