| 查看: 1106 | 回复: 2 | ||
p1801321金虫 (著名写手)
|
[求助]
求英译汉，机器翻译的不给金币哦
|
|
The defining phase transformation associated with the glassy state is the glass transition. However, this is not a thermodynamic phase transition at all, but rather a kinetic transformation as a liquid is supercooled. The glass transition involves a freezing of the configurational degrees of freedom at the nanoscale level such that the glass is a solid-like material but with liquid-like properties. In recent years, much progress has been made in understanding the fundamental physics of the glass transition. The glass transition itself is a function of both the structural relaxation time — an intrinsic property —and an external observation time scale (i.e., the relevant time scale of the experiment). Glass transition can be induced through either of two pathways. The first is by increasing the internal relaxation time of a glass forming liquid. This is what happens in the traditional approach to glass-forming by cooling from a high-temperature melt. As the temperature of the system is lowered, the atoms lose thermal energy, eventually becoming trapped in a particular configuration. The second path to induce glass transition is by shortening the observation time scale. Any liquid, when observed on a short enough time scale, will behave as a solid material, that is, a glass. This method of inducing glass transition is seen, for example, in specific heat spectroscopy experiments where a system is probed on a multitude of disparate time scales. The glass transition is fundamentally kinetic in origin, but it has important thermodynamic consequences. While the freezing of the configurational degrees of freedom during the glass transition does not result in any change in volume or energy, the configurational contributions to entropy and second-order thermodynamic properties such as heat capacity and thermal expansion coefficient are all lost as the system becomes frozen at the nanoscale level. This has led many scientists to postulate the existence of an “ideal” glass transition that entails a second-order thermodynamic phase transformation. However, the concept of an ideal glass transition has been widely criticized based on both theoretical and experimental considerations. While the glass transition involves the imposition of a kinetic constraint, the opposite process — structural relaxation — involves the lifting of this constraint. Because glass is a nonequilibrium material, it is continually relaxing to approach its metastable supercooled liquid state. At low temperatures and short time scales, this relaxation process is effectively frozen. However, at higher temperature or for exponentially longer times, measurable relaxation of the glassy state can be observed, reactivating the nanoscale transitions that ultimately lead to viscous flow. Relaxation is a spontaneous process and involves an increase in heat capacity, thermal expansion coefficient, and entropy as the configurational degrees of freedom of the system become activated. |
回复此楼» 猜你喜欢
面上可以超过30页吧？
已经有13人回复
-
网上报道青年教师午睡中猝死、熬夜猝死的越来越多，主要哪些原因引起的？
已经有10人回复
-
为什么中国大学工科教授们水了那么多所谓的顶会顶刊，但还是做不出宇树机器人？
已经有13人回复
-
什么是人一生最重要的？
已经有8人回复
-
版面费该交吗
已经有17人回复
-
体制内长辈说体制内绝大部分一辈子在底层，如同你们一样大部分普通教师忙且收入低
已经有19人回复
-
【博士招生】太原理工大学2026化工博士
已经有8人回复
-
280求调剂
已经有4人回复
2楼2020-10-17 11:27:13
★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ...
fjtony163: 金币-50, 严禁广告 2020-11-01 01:43:37
fjtony163: 金币-50, 版主自由裁量 广告贴屡犯 直接扣金币到负数 2020-11-01 01:44:18
fjtony163: 金币-50, 严禁广告 2020-11-01 01:44:25
fjtony163: 金币-50, 严禁广告 2020-11-01 01:44:30
fjtony163: 金币-50, 屏蔽内容, 严禁广告 2020-11-01 01:45:03
fjtony163: 金币-50, 严禁广告 2020-11-01 01:43:37
fjtony163: 金币-50, 版主自由裁量 广告贴屡犯 直接扣金币到负数 2020-11-01 01:44:18
fjtony163: 金币-50, 严禁广告 2020-11-01 01:44:25
fjtony163: 金币-50, 严禁广告 2020-11-01 01:44:30
fjtony163: 金币-50, 屏蔽内容, 严禁广告 2020-11-01 01:45:03
|
本帖内容被屏蔽 |
3楼2020-10-31 09:40:13