Hidden structural ordering in a supercooled liquid:
Intrinsic link between glass transition and crystallization
Hajime Tanaka, Takeshi Kawasaki, Hiroshi Shintani, and Keiji Watanabe
Institute of Industrial Science, The University of Tokyo, Meguro-ku, Tokyo 153-8505, Japan
Recently it has been revealed that when approaching the glass transition temperature Tg, liquid dynamics
not only drastically slow, but also become progressively more heterogeneous. From our simulations andexperiments of six different glass-forming liquids1-5, we find that the heterogeneous dynamics is a result ofcritical-like fluctuations of static structural order, contrary to a common belief that it is purely of dynamic
origin: The ‘static’ correlation length and susceptibility of a structural order parameter exhibit Ising-like
power-law divergence towards the ideal glass-transition point5. However, this structural ordering
accompanies little density change over a long range, which explains why it has not been detected by thestatic structure factor so far. Our results suggest a far more direct link than thought before, between glasstransition and critical phenomena: Glass transition may be a novel type of critical phenomena, where astructural order parameter is directly linked to slowness.
This critical-like structural ordering also has an important implication on crystallization, which
intrinsically takes place in a supercooled liquid state. For hard-sphere-like colloidal liquids, for example, wereveal that in a supercooled liquid state, medium-range crystalline bond orientational order of the hexagonalclose pack structure grows in its size and lifetime with increasing the packing fraction5,6. We reveal that
nucleation of crystals preferentially occurs in regions of high medium-range order, reflecting the low
crystal-liquid interfacial energy there6. These findings may shed new light not only on the fundamental
nature of glass transition, but also the mechanism of crystal nucleation. The relation of these findings to ourtwo-order-parameter model of glass transition7,8 will also be discussed.
REFERENCES
1. Shintani, H. and Tanaka, H. “Frustration on the way to crystallization in glass”, Nature Phys. 2,200(2006).
2. Kawasaki, T., Araki, T., and Tanaka, H. “Correlation between dynamic heterogeneity andmedium-range order in two-dimensional glass-forming liquids”, Phys. Rev. Lett. 99, 215701 (2007).
3. Watanabe, K. and Tanaka, H. “Direct observation of medium-range crystalline order in granular liquids
near the glass transition”, Phys. Rev. Lett. 100, 158002 (2008).
4. Shintani, H. and Tanaka, H. “Universal link between the boson peak and transverse phonons in glass”, NatureMater. 7, 870 (2008).
5. Tanaka, H., Kawasaki, T, Shintani, H. and Watanabe, K. “Critical-like behaviour of glass-forming liquids”,Nature Mater. 9, 324 (2010).
6. Kawasaki, T. and Tanaka, H. “Structural origin of dynamic heterogeneity in three-dimensional colloidal
glass formers and its link to crystal nucleation” (in press).
7. Tanaka, H. “Two-order-parameter description of liquids. I. A general model of glass transition covering its
strong to fragile limit”, J. Chem. Phys. 111, 3163 (1999).
8. Tanaka, H. “Two-order-parameter model of the liquid-glass transition. II. Structural relaxation anddynamic heterogeneity”, J. Non-Cryst. Solids 351, 3385 (2005).

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