Fast Crystal Growth Induces Mobility and Tension in Supercooled o-Terphenyl

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• 作者：Keewook Paeng ; C. Travis Powell ; Lian Yu ; M. D. Ediger
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2012
• 出版时间：September 20, 2012
• 年：2012
• 卷：3
• 期：18
• 页码：2562-2567
• 全文大小：356K
• 年卷期：v.3,no.18(September 20, 2012)
• ISSN：1948-7185

文摘

A photobleaching method was used to measure the reorientation of dilute probes in liquid o-terphenyl near a crystal growth front. Near the glass-transition temperature T_g, mobility in the supercooled liquid was enhanced within 10 渭m of the crystal growth front, by as much as a factor of 4. This enhanced mobility appears to be caused by tension created in the sample as a result of the density difference between the supercooled liquid and crystal. The maximum observed mobility enhancement corresponds to a tension of about 鈭? MPa, close to the cavitation limit for liquid o-terphenyl. Whereas the observed mobility near the growing crystal is not large enough to explain the extraordinary fast crystal growth observed near T_g in o-terphenyl and some other low-molecular-weight glassformers, these observations suggest that cavitation or fracture plays a key role in releasing tension and allowing fast crystal growth to occur at a steady rate.

Keywords:

GC crystal; organic glassformers; molecular mobility; rotational diffusion