New Materials for Optical Amplifiers

Ellison, Adam J.; Minelly, J.D.

doi:10.1016/b978-012395172-4/50003-6

Cited by 3 publications

(3 citation statements)

References 190 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Even though a glass is structurally arrested (with particles largely caged by their neighbours), it may crystallize in a process known as devitrification. Since controlling crystallization is a major challenge in stabilising glassy materials (e. g. metallic and ceramic glasses [1][2][3][4]), a better mechanistic understanding of how a deeply-arrested amorphous material transforms into a crystal is still needed.…”

Section: Introductionmentioning

confidence: 99%

Avalanche mediated devitrification in a glass of pseudo hard-spheres

Rosales-Pelaez¹,

Hijes²,

Sanz³

et al. 2016

J. Stat. Mech.

View full text Add to dashboard Cite

By means of molecular dynamics we analyse several aspects of the avalanche-mediated mechanism for glass crystallization recently reported for hard sphere glasses (Sanz et al 2014 Proc. Natl Acad. Sci. 111 75). To investigate the role of inter-particle interaction softness on the devitrification path we use a continuous version of the hard-sphere potential: the pseudo-hard sphere potential (Jover et al 2012 J. Chem. Phys. 137 144505). We observe the same crystallization mechanism as in hard spheres. However, pseudo-hard sphere glasses crystallise earlier for a given density because the development of avalanches is eased by the small degree of overlapping allowed. We analyse the impact of density on the devitrification mechanism. When increasing the density, the avalanche mechanism becomes more evident and crystallisation is retarded due to a decrease of the avalanche emergence likelihood. To conclude, the observed avalanche-mediated mechanism and its density dependence do not substantially change with the employed simulation ensemble (constant volume versus constant pressure).

show abstract

Section: Introductionmentioning

confidence: 99%

Avalanche mediated devitrification in a glass of pseudo hard-spheres

Rosales-Pelaez¹,

Hijes²,

Sanz³

et al. 2016

J. Stat. Mech.

View full text Add to dashboard Cite

show abstract

“…Devitrification is a phenomenon of both fundamental interest (2, 3) and practical importance (4)(5)(6)(7)(8)(9)(10). Indeed, the prediction and avoidance or control of devitrification represent major formulation issues in materials science, arising for both metallic (4-6) and network glasses (7,8) as well as glass ceramics (9, 10).…”

mentioning

confidence: 99%

“…Indeed, the prediction and avoidance or control of devitrification represent major formulation issues in materials science, arising for both metallic (4-6) and network glasses (7,8) as well as glass ceramics (9, 10). So far, however, there is limited understanding of the mechanisms whereby an apparently deeply arrested amorphous material can transform itself into a crystalline packing without the large-scale, diffusive particle motions whose absence [stemming from the formation of cages (11)] is a defining property of glasses.…”

mentioning

confidence: 99%

Avalanches mediate crystallization in a hard-sphere glass

Sanz

Valeriani

Zaccarelli

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

By molecular-dynamics simulations, we have studied the devitrification (or crystallization) of aged hard-sphere glasses. First, we find that the dynamics of the particles are intermittent: Quiescent periods, when the particles simply "rattle" in their nearest-neighbor cages, are interrupted by abrupt "avalanches," where a subset of particles undergo large rearrangements. Second, we find that crystallization is associated with these avalanches but that the connection is not straightforward. The amount of crystal in the system increases during an avalanche, but most of the particles that become crystalline are different from those involved in the avalanche. Third, the occurrence of the avalanches is a largely stochastic process. Randomizing the velocities of the particles at any time during the simulation leads to a different subsequent series of avalanches. The spatial distribution of avalanching particles appears random, although correlations are found among avalanche initiation events. By contrast, we find that crystallization tends to take place in regions that already show incipient local order.colloidal glasses | ordered solid | amorphous solid | dynamic heterogeneities G lasses are formed from the supercooled liquid state when motion is arrested on the scale of the particle diameter. Such states are thermodynamically unstable and may crystallize during, or shortly after, the initial quench. (This is the usual fate of so-called "poor" glass formers.)Computer simulations have shown that, in such cases, crystallization readily proceeds by a sequence of stochastic micronucleation events that enhance the mobility in neighboring areas, leading to a positive feedback for further crystallization (1). Importantly, however, crystallization can also arise in mature, well-formed glasses after a long period of apparent stability. The microscopic mechanism of this process, known as "devitrification," remains elusive. Here, we simulate the dynamics of a mature hard-sphere glass and find that crystallization is associated with a series of discrete avalanche-like events characterized by a spatiotemporal burst of particle displacements on a subdiameter scale. The locations of these avalanches cannot be predicted from the prior structure of the glass, and they vary among replicate runs that differ only in initial particle velocities. Each avalanche leads to a sharp increase in crystallinity, but remarkably the crystallizing particles are primarily not those that participated in the avalanche itself. Instead, they tend to lie in nearby regions that are already partially ordered. We argue that a structural propensity to crystallize in these regions is converted into actual crystallinity by small random disturbances provided by the displacement avalanche. Although spontaneous rather than externally imposed, this pathway may relate to designed crystallization protocols such as oscillatory shear.Devitrification is a phenomenon of both fundamental interest (2, 3) and practical importance (4-10). Indeed, the prediction and avoidance...

show abstract