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Five-fold symmetry as indicator of dynamic arrest in metallic glass-forming liquids.

Hu YC, Li FX, Li MZ, Bai HY, Wang WH - Nat Commun (2015)

Bottom Line: Because of the intricate atomic structure and dynamic behaviours of liquid, it is yet difficult to capture the underlying structural mechanism responsible for the marked slowing down during glass transition, which impedes deep understanding of the formation and nature of glasses.Here, we report that a universal structural indicator, the average degree of five-fold local symmetry, can well describe the slowdown dynamics during glass transition.A straightforward relationship between structural parameter and viscosity (or α-relaxation time) is introduced to connect the dynamic arrest and the underlying structural evolution.

View Article: PubMed Central - PubMed

Affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing 100190 China.

ABSTRACT
With sufficient high cooling rates, a variety of liquids, including metallic melts, will cross a glass transition temperature and solidify into glass accompanying a marked increase of the shear viscosity in approximately 17 orders of magnitude. Because of the intricate atomic structure and dynamic behaviours of liquid, it is yet difficult to capture the underlying structural mechanism responsible for the marked slowing down during glass transition, which impedes deep understanding of the formation and nature of glasses. Here, we report that a universal structural indicator, the average degree of five-fold local symmetry, can well describe the slowdown dynamics during glass transition. A straightforward relationship between structural parameter and viscosity (or α-relaxation time) is introduced to connect the dynamic arrest and the underlying structural evolution. This finding would be helpful in understanding the long-standing challenges of glass transition mechanism in the structural perspective.

No MeSH data available.


Related in: MedlinePlus

Relationship between viscosity and average five-fold local symmetry.(a) The variation of W and the shear viscosity with temperature for Cu50Zr50 metallic liquid. The inset shows the normalized shear auto-correlation function, which was used to calculate the shear viscosity; (b) shear viscosity η versus W. The dotted lines are obtained from simulations and the solid line is the fitting by equation (3); in the insets (i) and (ii), the open and solid circles show the temperature dependence of W and η, respectively, and the solid lines are fitting of the power-law and VFT functions, respectively.
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f2: Relationship between viscosity and average five-fold local symmetry.(a) The variation of W and the shear viscosity with temperature for Cu50Zr50 metallic liquid. The inset shows the normalized shear auto-correlation function, which was used to calculate the shear viscosity; (b) shear viscosity η versus W. The dotted lines are obtained from simulations and the solid line is the fitting by equation (3); in the insets (i) and (ii), the open and solid circles show the temperature dependence of W and η, respectively, and the solid lines are fitting of the power-law and VFT functions, respectively.

Mentions: To clarify the relation between dynamics and structure, the shear viscosity was calculated for the model system of Cu50Zr50 metallic liquid with the equilibrium MD (Green–Kubo theorem) method based on the shear auto-correlation function31 (as shown in the inset of Fig. 2a),


Five-fold symmetry as indicator of dynamic arrest in metallic glass-forming liquids.

Hu YC, Li FX, Li MZ, Bai HY, Wang WH - Nat Commun (2015)

Relationship between viscosity and average five-fold local symmetry.(a) The variation of W and the shear viscosity with temperature for Cu50Zr50 metallic liquid. The inset shows the normalized shear auto-correlation function, which was used to calculate the shear viscosity; (b) shear viscosity η versus W. The dotted lines are obtained from simulations and the solid line is the fitting by equation (3); in the insets (i) and (ii), the open and solid circles show the temperature dependence of W and η, respectively, and the solid lines are fitting of the power-law and VFT functions, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4595736&req=5

f2: Relationship between viscosity and average five-fold local symmetry.(a) The variation of W and the shear viscosity with temperature for Cu50Zr50 metallic liquid. The inset shows the normalized shear auto-correlation function, which was used to calculate the shear viscosity; (b) shear viscosity η versus W. The dotted lines are obtained from simulations and the solid line is the fitting by equation (3); in the insets (i) and (ii), the open and solid circles show the temperature dependence of W and η, respectively, and the solid lines are fitting of the power-law and VFT functions, respectively.
Mentions: To clarify the relation between dynamics and structure, the shear viscosity was calculated for the model system of Cu50Zr50 metallic liquid with the equilibrium MD (Green–Kubo theorem) method based on the shear auto-correlation function31 (as shown in the inset of Fig. 2a),

Bottom Line: Because of the intricate atomic structure and dynamic behaviours of liquid, it is yet difficult to capture the underlying structural mechanism responsible for the marked slowing down during glass transition, which impedes deep understanding of the formation and nature of glasses.Here, we report that a universal structural indicator, the average degree of five-fold local symmetry, can well describe the slowdown dynamics during glass transition.A straightforward relationship between structural parameter and viscosity (or α-relaxation time) is introduced to connect the dynamic arrest and the underlying structural evolution.

View Article: PubMed Central - PubMed

Affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing 100190 China.

ABSTRACT
With sufficient high cooling rates, a variety of liquids, including metallic melts, will cross a glass transition temperature and solidify into glass accompanying a marked increase of the shear viscosity in approximately 17 orders of magnitude. Because of the intricate atomic structure and dynamic behaviours of liquid, it is yet difficult to capture the underlying structural mechanism responsible for the marked slowing down during glass transition, which impedes deep understanding of the formation and nature of glasses. Here, we report that a universal structural indicator, the average degree of five-fold local symmetry, can well describe the slowdown dynamics during glass transition. A straightforward relationship between structural parameter and viscosity (or α-relaxation time) is introduced to connect the dynamic arrest and the underlying structural evolution. This finding would be helpful in understanding the long-standing challenges of glass transition mechanism in the structural perspective.

No MeSH data available.


Related in: MedlinePlus