Rheology of the λ transition in liquid sulfur: Insights from arsenic sulfide liquids.
Rheology of the λ transition in liquid sulfur: Insights from arsenic sulfide liquids.
复制标题
液体硫中 λ 转变的流变学：来自硫化砷液体的见解。
作者：
Weidi Zhu;M. Lockhart;B. Aitken;S. Sen
使用平行板流变测定法在覆盖近 15 个数量级的频率范围内获得了 AsxS100-x 玻璃形成液体 (x = 5、10、15、40) 的存储和损耗剪切模量以及粘度的频率依赖性。富硫（x ≤ 15）液体的特征是在 Tλ ∼ 120 °C 附近发生环链结构转变，并且它们在低于 Tλ 的流变行为与长链和缠结聚合物以及最近推测的高于其 λ 转变的液体硫的流变行为非常相似。这些 AsxS100-x 液体的特点是具有相似活化能的慢弛豫过程和快速弛豫过程并存。这两个过程都与粘度耦合，但时间尺度相差几个数量级，并分别分配给这些液体中 Sn 链的蠕动和劳斯动力学。这种复杂的类似聚合物的流变行为在 As40S60 液体中消失了，其特征是共享角的 AsS3/2 金字塔，而出现了简单液体典型的单一平均剪切弛豫时间。
The frequency dependence of the storage and loss shear moduli and viscosity of AsxS100-x glass-forming liquids (x = 5, 10, 15, 40) are obtained over a frequency range covering nearly 15 orders of magnitude using parallel plate rheometry. The S-rich (x ≤ 15) liquids are characterized by a ring-to-chain structural transition near Tλ ∼ 120 °C, and their rheological behavior below Tλ strongly resembles that of long-chain and entangled polymers as well as that recently speculated for liquid sulfur above its λ transition. These AsxS100-x liquids are characterized by the coexistence of a slow and a fast relaxation process with similar activation energy. Both processes are coupled to viscosity, but differ in time scale by several orders in magnitude and are assigned, respectively, to the reptation and the Rouse dynamics of the Sn chains in these liquids. Such complex polymer-like rheological behavior disappears in the As40S60 liquid, characterized by corner-shared AsS3/2 pyramids, where a single average shear relaxation time typical of simple liquids instead emerges.