scholarly journals Physical origin of glass formation from multicomponent systems

2020 ◽  
Vol 6 (50) ◽  
pp. eabd2928
Author(s):  
Yuan-Chao Hu ◽  
Hajime Tanaka
Keyword(s):  
Phase Change ◽  
Glass Formation ◽  
Phase Change Materials ◽  
Multicomponent Systems ◽  
Physical Origin ◽  
Interface Tension ◽  
Switching Speed ◽  
Glass Forming ◽  
Nontrivial Coupling ◽  
Dynamics Simulations

The origin of glass formation is one of the most fundamental issues in glass science. The glass-forming ability (GFA) of multicomponent systems, such as metallic glasses and phase-change materials, can be enormously changed by slight modifications of the constituted elements and compositions. However, its physical origin remains mostly unknown. Here, by molecular dynamics simulations, we study three model metallic systems with distinct GFA. We find that they have a similar driving force of crystallization, but a different liquid-crystal interface tension, indicating that the latter dominates the GFA. Furthermore, we show that the interface tension is determined by nontrivial coupling between structural and compositional orderings and affects crystal growth. These facts indicate that the classical theories of crystallization need critical modifications by considering local ordering effects. Our findings provide fresh insight into the physical control of GFA of metallic alloys and the switching speed of phase-change materials without relying on experience.

An engineering model for high-speed switching in GeSbTe phase-change memory

2022 ◽  
Author(s):  
Junji TOMINAGA
Keyword(s):  
Phase Change ◽  
High Speed ◽  
High Performance ◽  
Ab Initio Molecular Dynamics ◽  
Switching Speed ◽  
Non Volatile Memory ◽  
Crystal Transition ◽  
Dynamics Simulations ◽  
High Speed Switching ◽  
Successful Phase

Abstract Ge2Sb2Te5 is the most successful phase-change alloy in non-volatile memory using the amorphous-crystal phase transition. In deriving further high performance in switching, especially SET speed (from amorphous to crystal transition) should still be modified. In this work, It was examined an ideal Ge2Sb2Te5 alloy based on the Kolobov model using ab-initio molecular dynamics simulations. As a result, it was cleared that a uniaxial exchange between vacancies and Ge atoms is the crucial role in realizing high-speed switching and a large contrast in the resonance bonding state in the alloy. The vacancy engineering enables the alloy switching speed extremely faster.

Interatomic potential to predict the binary metallic glass formation

2010 ◽  
Vol 25 (5) ◽  
pp. 976-981 ◽  
Author(s):  
Baixin Liu ◽  
Jiahao Li ◽  
Wensheng Lai
Keyword(s):  
Metallic Glass ◽  
Glass Formation ◽  
Composition Range ◽  
Interatomic Potential ◽  
Thermodynamic Characteristics ◽  
Crystalline Lattice ◽  
Interatomic Potentials ◽  
Glass Forming ◽  
Binary Metal ◽  
Dynamics Simulations

Interatomic potentials are constructed for eight representative binary metal systems covering various structural combinations and thermodynamic characteristics. On the basis of the constructed interatomic potentials, molecular dynamics simulations reveal that the physical origin of metallic glass formation is the crystalline lattice collapsing while solute atoms are exceeding the critical value, thus determining two critical solid solubilities for the system. For a binary metal system, the composition range bounded by the two determined critical solid solubilities is therefore defined as its intrinsic glass-forming range, or quantitative glass-forming ability.

Universal localization transition accompanying glass formation: insights from efficient molecular dynamics simulations of diverse supercooled liquids

Soft Matter ◽  
2019 ◽  
Vol 15 (6) ◽  
pp. 1223-1242 ◽  
Author(s):  
Jui-Hsiang Hung ◽  
Tarak K. Patra ◽  
Venkatesh Meenakshisundaram ◽  
Jayachandra Hari Mangalara ◽  
David S. Simmons
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
High Throughput ◽  
Glass Formation ◽  
Supercooled Liquids ◽  
Localization Transition ◽  
Glass Forming ◽  
Particle Localization ◽  
Dynamics Simulations ◽  
Universal Localization

High-throughput simulations reveal a universal onset of particle localization in diverse glass-forming liquids.

Atomistic Simulations of Phase Change Materials for Electronic Memories

2019 ◽  
Vol 18 (03n04) ◽  
pp. 1940082
Author(s):  
M. Bernasconi
Keyword(s):  
Phase Change ◽  
Density Functional ◽  
Large Scale ◽  
Phase Change Materials ◽  
Interatomic Potential ◽  
Supercooled Liquid ◽  
Atomistic Simulations ◽  
Artificial Neural Network Method ◽  
Dynamics Simulations ◽  
Methodological Advance

We review our results on large-scale atomistic simulations of the phase change compound GeTe of interest for applications in nonvolatile electronic memories. The simulations are based on an interatomic potential with an accuracy close to that of the density functional theory (DFT). The potential was generated by fitting a DFT database by means of an artificial neural network method. This methodological advance allowed us to perform molecular dynamics simulations with several thousand atoms for several ns that provided useful insights on several properties of interest for the operation of phase change memories, including the crystallization kinetics, the dynamics of the supercooled liquid, the structural relaxation in the glass and the properties of nanowires.

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