Structural and dynamic origin of the boson peak in a Cu-Zr metallic glass

Jakse, N.; Nassour, Ayoub; Pasturel, A.

doi:10.1103/physrevb.85.174201

Cited by 36 publications

(31 citation statements)

References 50 publications

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“…These low-frequency modes are detected as a peak in the low temperature (5-15 K) heat capacity C plotted as C/T 3 vs. T. These features are usually referred to as the boson peak, which is known for metallic glasses as well [67]. The nature of the boson peak constitutes a matter of intensive ongoing debates [68][69][70][71]. Granato argued that the boson peak originates from low-frequency resonance vibration modes of interstitial-type defects frozen-in upon glass production [72].…”

Section: Relation Of the Boson Heat Capacity Peak To The Defect Strucmentioning

confidence: 99%

Metallic Glasses: A New Approach to the Understanding of the Defect Structure and Physical Properties

Khonik

Кобелев

2019

Metals

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The work is devoted to a brief overview of the Interstitialcy Theory (IT) as applied to different relaxation phenomena occurring in metallic glasses upon structural relaxation and crystallization. The basic hypotheses of the IT and their experimental verification are shortly considered. The main focus is given on the interpretation of recent experiments on the heat effects, volume changes and their link with the shear modulus relaxation. The issues related to the development of the IT and its relationship with other models on defects in metallic glasses are discussed.

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Section: Relation Of the Boson Heat Capacity Peak To The Defect Strucmentioning

confidence: 99%

Metallic Glasses: A New Approach to the Understanding of the Defect Structure and Physical Properties

Khonik

Кобелев

2019

Metals

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“…The remaining question is, if the defect-based boson peak models are indeed as different as they initially appear to be. Studies ascribe the boson peak to interstitialcies [14,15], "liquidlike" regions [13,25], "rattling" atoms [11,12], and of course fluctuating force constants [17-19, 21, 22]. So, in addition to local shear moduli, we calculated the mean square displacement (MSD) of the atoms at 30 K over a period of 100 ps.…”

Section: Connection Between Defective Structures and Softeningmentioning

confidence: 99%

“…The latter assumes an interaction of acoustic phonons with quasi-localized modes arising from "defects" in the disordered structure [7][8][9]. It was proposed that these defects are loosely packed atoms [6,[10][11][12][13] or resemble interstitialcies [14,15]. An alternative explanation, where the boson peak is considered to be a precursor of a dynamical instability, was brought forward by Grigera et al [16], while Schirmacher and colleagues developed a theory where fluctuating force or elastic constants give rise to the additional modes that make up the boson peak [17][18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Structural origins of the boson peak in metals: From high-entropy alloys to metallic glasses

2016

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The boson peak appears in all amorphous solids and is an excess of vibrational states at low frequencies compared to the phonon spectrum of the corresponding crystal. Until recently, the consensus was that it originated from "defects" in the glass. The nature of these defects is still under discussion, but the picture of regions with locally disturbed short-range order and/or decreased elastic constants has gained some traction. Recently, a different theory was proposed: The boson peak was attributed to the first van Hove singularity of crystal lattices which is only smeared out by the disorder. This new viewpoint assumes that the van Hove singularity is simply shifted by the decreased density of the amorphous state and is therefore not a glass-specific anomaly. In order to resolve this issue, we use computer models of a four-component alloy, alternatively with chemical disorder (high-entropy alloy), structural disorder, and reduced density. Comparison to a reference glass of the same composition reveals that the boson peak consists of additional vibrational modes which can be induced solely by structural disorder. While chemical disorder introduces fluctuations of the elastic constants, we find that those do not lead to sufficient local softening to induce these modes. A boson peak due to a reduction of density could be excluded for the present metallic system.

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“…At a very low temperature (<100 K) or very short observation time (~10 -12 s), the atoms mainly vibrate around their equilibrium positions and contribute to the well-known boson peak [49]. While temperature increases (~100 K-500 K in our work) or time lengthens (~10 -10 s), some atoms with relatively large LCA undergo reversible motions inside the FNSs and activate the reversible transition between two neighboring subbasins.…”

Section: A Holistic Picture To Understand the Relaxation Modes In Mgsmentioning

confidence: 63%

Revealing the Low-Temperature Fast Relaxation Peak in a Model Metallic Glass

Wang

Shang

et al. 2020

SSRN Journal

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By systematically investigating the relaxation behavior of a model metallic glass based on the extensive molecular dynamics (MD) simulations combined with the dynamic mechanical spectroscopy method, a pronounced ultra-low temperature peak on the loss modulus spectrum was discovered for the first time in MD simulations. It was found that the relation peak occurs at a much lower temperature than the typical temperature for the conventional β relation peak as reported in the literature. According to the atomic displacement analysis, we unravel that the reversible atomic motions, rather than the thermal vibrations or local structural rearrangements, mainly contribute to this relaxation peak. We further identify the atomic level mechanism of this fast relaxation process by characterizing the local geometrical anisotropy. Furthermore, by tracing the dynamic behaviors of these "reversible" atoms, we demonstrate the intrinsic hierarchy of the local relaxation modes, which are triggered by atomic vibrations and gradually developed to the reversible and irreversible atomic movements. Our findings shed light on a general picture of the relaxation processes in metallic glasses.

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Structural and dynamic origin of the boson peak in a Cu-Zr metallic glass

Cited by 36 publications

References 50 publications

Metallic Glasses: A New Approach to the Understanding of the Defect Structure and Physical Properties

Metallic Glasses: A New Approach to the Understanding of the Defect Structure and Physical Properties

Structural origins of the boson peak in metals: From high-entropy alloys to metallic glasses

Revealing the Low-Temperature Fast Relaxation Peak in a Model Metallic Glass

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