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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

Correlation between specific heat CP and W.(a) The temperature dependence of the specific heat CP for various systems. (b) The structural change rate during quenching reflected by dW/dT shows a jump during glass transition. The coincidence of the excess specific heat and the jump in dW/dT illustrates the structural basis of the thermodynamics (the same colour in a,b represents the same system).
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f7: Correlation between specific heat CP and W.(a) The temperature dependence of the specific heat CP for various systems. (b) The structural change rate during quenching reflected by dW/dT shows a jump during glass transition. The coincidence of the excess specific heat and the jump in dW/dT illustrates the structural basis of the thermodynamics (the same colour in a,b represents the same system).

Mentions: It is commonly believed that vitrification is a result of extreme difficulty in crystal nucleation and growth, during which thermodynamics is also crucial. According to Adam-Gibbs theory41, the dynamics correlates strongly with configurational entropy, which is controlled by structural evolution. To unravel the connection among dynamics, thermodynamics and structure, we investigated the correlation between five-fold local symmetry and specific heat. Here the isobaric-specific heat CP was calculated in terms of its definition, , where H is the enthalpy4243. Figure 7a shows the typical temperature dependence of CP during glass transition. Here temperature is scaled by Tg. During quenching CP increases and reaches a maximum, then decreases. An excess specific heat was observed in Fig. 7a. If one takes a derivative of W, dW/dT, a similar jump behaviour is also observed in the change rate of the W parameter, as shown in Fig. 7b, indicating that there exists a correlation between the thermodynamics and the structure evolution during the glass transition.


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)

Correlation between specific heat CP and W.(a) The temperature dependence of the specific heat CP for various systems. (b) The structural change rate during quenching reflected by dW/dT shows a jump during glass transition. The coincidence of the excess specific heat and the jump in dW/dT illustrates the structural basis of the thermodynamics (the same colour in a,b represents the same system).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f7: Correlation between specific heat CP and W.(a) The temperature dependence of the specific heat CP for various systems. (b) The structural change rate during quenching reflected by dW/dT shows a jump during glass transition. The coincidence of the excess specific heat and the jump in dW/dT illustrates the structural basis of the thermodynamics (the same colour in a,b represents the same system).
Mentions: It is commonly believed that vitrification is a result of extreme difficulty in crystal nucleation and growth, during which thermodynamics is also crucial. According to Adam-Gibbs theory41, the dynamics correlates strongly with configurational entropy, which is controlled by structural evolution. To unravel the connection among dynamics, thermodynamics and structure, we investigated the correlation between five-fold local symmetry and specific heat. Here the isobaric-specific heat CP was calculated in terms of its definition, , where H is the enthalpy4243. Figure 7a shows the typical temperature dependence of CP during glass transition. Here temperature is scaled by Tg. During quenching CP increases and reaches a maximum, then decreases. An excess specific heat was observed in Fig. 7a. If one takes a derivative of W, dW/dT, a similar jump behaviour is also observed in the change rate of the W parameter, as shown in Fig. 7b, indicating that there exists a correlation between the thermodynamics and the structure evolution during the glass transition.

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