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Separating the configurational and vibrational entropy contributions in metallic glasses
Nature Physics ( IF 17.6 ) Pub Date : 2017-05-29 00:00:00 , DOI: 10.1038/nphys4142
Hillary L. Smith , Chen W. Li , Andrew Hoff , Glenn R. Garrett , Dennis S. Kim , Fred C. Yang , Matthew S. Lucas , Tabitha Swan-Wood , J. Y. Y. Lin , M. B. Stone , D. L. Abernathy , Marios D. Demetriou , B. Fultz

Glassy materials exist in nature and play a critical role in technology, but key differences between the glass, liquid and crystalline phases are not well understood. Over several decades there has been controversy about the specific heat absorbed as a glass transforms to a liquid—does this originate from vibrational entropy or configurational entropy? Here we report direct in situ measurements of the vibrational spectra of strong and fragile metallic glasses in the glass, liquid and crystalline phases. For both types of material, the measured vibrational entropies of the glass and liquid show a tiny excess over the crystal, representing less than 5% of the total excess entropy measured with step calorimetry. These results reveal that the excess entropy of metallic glasses is almost entirely configurational in origin, consistent with the early theories of Gibbs and co-workers describing the glass transition as a purely configurational transition.

中文翻译:

分离金属玻璃的构型和振动熵贡献

玻璃质材料存在于自然界中,并在技术中起着至关重要的作用,但是人们对玻璃,液相和结晶相之间的关键区别还不太了解。几十年来,关于玻璃转化为液体时吸收的比热一直存在争议-这是源自振动熵还是构型熵?在这里,我们直接就地报告在玻璃,液相和结晶相中测量强而易碎的金属玻璃的振动光谱。对于这两种类型的材料,所测量的玻璃和液体的振动熵都比晶体略微过量,占不到用逐步量热法测量的总过量熵的5%。这些结果表明,金属玻璃的过量熵几乎完全是构型的,这与吉布斯及其同事将玻璃化转变描述为纯结构化转变的早期理论是一致的。
更新日期:2017-09-05
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