Suppression of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>β</mml:mi></mml:math>Relaxation in Vapor-Deposited Ultrastable Glasses

Yu, Hai Bin; Tylinski, M.; Guiseppi‐Elie, Anthony; Ediger, M. D.; Richert, Ranko

doi:10.1103/physrevlett.115.185501

Cited by 121 publications

(122 citation statements)

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“…In conclusion, our observations may explain why some anomalies characteristic of amorphous solids are suppressed in ultra-stable glasses, but more work is needed to relate precisely the anomalies observed in our numerically simulated samples to the ones observed in experiments [18][19][20][21][22]. Moreover, finite size effects, and in particular the dependence of our results on films' thickness, remain to be investigated.…”

Section: Discussionmentioning

confidence: 96%

“…Compared to their liquid-cooled counterparts, vapor-deposited glasses show higher density [16] and kinetic stability [15,17]. When these ultra-stable glasses are studied at very low temperatures, it is found that the anomalies characteristic of amorphous solids are strongly supressed [18][19][20][21][22].Many theoretical approaches to this problem are based on the study of the potential energy landscape of glassforming particle systems [13,[23][24][25][26][27][28]. These studies have suggested that glass anomalies can be interpreted in terms of glass states being not well-defined energy minima, but structured metabasins containing a collection of sub-basins separated by barriers of variable size [29,30], see Fig.…”

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confidence: 99%

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Low-temperature anomalies of a vapor deposited glass

Seoane

Reid

Pablo

et al. 2018

Phys. Rev. Materials

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We investigate the low temperature properties of two-dimensional Lennard-Jones glass films, prepared in silico both by liquid cooling and by physical vapor deposition. We identify deep in the solid phase a crossover temperature T * , at which slow dynamics and enhanced heterogeneity emerge. Around T * , localized defects become visible, leading to vibrational anomalies as compared to standard solids. We find that on average, T * decreases in samples with lower inherent structure energy, suggesting that such anomalies will be suppressed in ultra-stable glass films, prepared both by very slow liquid cooling and vapor deposition.Low-temperature crystalline solids are usually described in terms of harmonic vibrations around a perfect periodic lattice (phonons). Within this framework, defects such as vacancies and dislocations can be treated as small perturbations. This description breaks down for amorphous solids such as glasses, foams, emulsions, plastics, colloids, granular materials, bacterial colonies, and tissues [1][2][3][4][5][6][7]. In these systems, the identification of "defects" becomes challenging because the solid ground state is strongly disordered. As a consequence, amorphous solids display many universal anomalies with respect to crystals. Examples are the so-called Boson Peak, an excess of low-energy vibrational modes [8]; the anomalous scaling of heat capacity and thermal conductivity with temperature [9,10]; the irreversible plastic response to arbitrarily small perturbations [1,3,4,11]; and highly cooperative relaxation dynamics, contributing to the socalled β-processes [12][13][14].These anomalies have been widely reported in amorphous solids of very different nature. Interestingly, recent experimental work has shown that by preparing glasses through a process of physical vapor deposition, one can produce ultra-stable states that lie deep in the free energy landscape [15]. Compared to their liquid-cooled counterparts, vapor-deposited glasses show higher density [16] and kinetic stability [15,17]. When these ultra-stable glasses are studied at very low temperatures, it is found that the anomalies characteristic of amorphous solids are strongly supressed [18][19][20][21][22].Many theoretical approaches to this problem are based on the study of the potential energy landscape of glassforming particle systems [13,[23][24][25][26][27][28]. These studies have suggested that glass anomalies can be interpreted in terms of glass states being not well-defined energy minima, but structured metabasins containing a collection of sub-basins separated by barriers of variable size [29,30], see Fig. 1. In particular, recent work [31][32][33] has identified a set of simple observables (the mean square displacement between identical "clones" of the original system) that allows one to detect easily the development of a structure of sub-basins inside a glass metabasin.In this work, using the methods of [31-33], we explore in silico the potential energy landscape of binary Lennard-Jones glass films prepared through tw...

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Section: Discussionmentioning

confidence: 96%

mentioning

confidence: 99%

Low-temperature anomalies of a vapor deposited glass

Seoane

Reid

Pablo

et al. 2018

Phys. Rev. Materials

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“…This finding implies that it is possible to tailor the mechanical properties of metallic glasses or polymers by controlling the  relaxation. [95] Boson peak is also a hot topic of fundamental research pertaining to the dynamic relaxation behavior of amorphous materials. However, its structural origin in metallic glasses is under intense debate.…”

Section: Fast  Relaxation Of Metallic Glassesmentioning

confidence: 99%

“…The dashed line is for the ultrastable glass. [95] Reprinted figure with permission from (Ref. 95), Copyright (2015) by the American Physical Society.…”

Section: Fig1mentioning

confidence: 99%

Amorphous physics and materials: Secondary relaxation and dynamic heterogeneity in metallic glasses: A brief review

et al. 2017

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/ 24Understanding mechanical relaxation, such as primary ( and secondary (relaxation, is key to unravel the intertwined relation between the atomic dynamics and non-equilibrium thermodynamics in metallic glasses. At a fundamental level, relaxation, plastic deformation, glass transition and crystallization of metallic glasses are intimately linked to each other, which can be related to atomic packing, inter-atomic diffusion and cooperative atom movement. Conceptually,  relaxation is usually associated with structural heterogeneities intrinsic to metallic glasses.However, the details of such structural heterogeneities, being masked by the meta-stable disordered long-range structure, are yet to be understood. In this paper, we briefly review the recent experimental and simulation results that were attempted to elucidate structural heterogeneities in metallic glasses within the framework of  relaxation. In particular, we will discuss the correlation among  relaxation, structural heterogeneity and mechanical properties of metallic glasses.

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“…Among the SGs produced by vapor deposition, only the SG of toluene 36,37 has been studied by dielectric relaxation and reported. 38 Toluene is a rigid molecule and its sole secondary relaxation is the JG b-relaxation. 28 The relationship between the a-and the b-relaxations of toluene is in accord with the CM eqn (1) The experimental data of t b (T) of a toluene SG deposited at a substrate temperature 98 K (= 0.84T g ) from Yu et al 38 are reproduced in Fig.…”

Section: Sgmentioning

confidence: 99%

Why is surface diffusion the same in ultrastable, ordinary, aged, and ultrathin molecular glasses?

Ngai

Paluch

Rodríguez-Tinoco

2017

Phys. Chem. Chem. Phys.

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Recently Fakhraai and coworkers measured surface diffusion in ultrastable glass produced by vapor deposition, ordinary glass with and without physical aging, and ultrathin films of the same molecular glassformer, N,N 0 -bis(3-methylphenyl)-N,N 0 -diphenylbenzidine (TPD). Diffusion on the surfaces of all these glasses is greatly enhanced compared with the bulk diffusion similar to that previously found by others, but remarkably the surface diffusion coefficients D S measured are practically the same. The observed independence of D S from changes of structural a-relaxation due to densification or finite-size effect has an impact on the current understanding of the physical origin of enhanced surface diffusion. We have demonstrated before and also here that the primitive relaxation time t 0 of the coupling model, or its analogue t b , the Johari-Goldstein b-relaxation, can explain quantitatively the enhancement found in ordinary glasses. In this paper, we assemble together considerable experimental evidence to show that the changes in t b and t 0 of ultrastable glasses, aged ordinary glasses, and ultrathin-films are all insignificant when compared with ordinary glasses. Thus, in the context of the explanation of the enhanced surface diffusion given by the coupling model, these collective experimental facts on t b and t 0 further explain approximately the same D S in the different glasses of TPD as found by Fakhraai and coworkers.

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Suppression ofβRelaxation in Vapor-Deposited Ultrastable Glasses

Cited by 121 publications

References 48 publications

Low-temperature anomalies of a vapor deposited glass

Low-temperature anomalies of a vapor deposited glass

Amorphous physics and materials: Secondary relaxation and dynamic heterogeneity in metallic glasses: A brief review

Why is surface diffusion the same in ultrastable, ordinary, aged, and ultrathin molecular glasses?

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