中等密度的无形冰揭示了切割速率,作为水相位图中的新维度
Ingrid de Almeida Ribeiro1, Debdas Dhabal1, Rajat Kumar1
1Department of Chemistry, The University of Utah, Salt Lake City, UT 84112-0850.
概括
研究人员发现了一种新的无形冰阶段,即剪切驱动的无形冰 (SDA),通过模拟剪切下的冰. 这一发现扩大了我们对水的理解.
科学领域:
- 物理化学 物理化学
- 材料科学是一种材料科学.
- 凝聚物质物理学 凝聚物质物理学
背景情况:
- 水表现出复杂的相位行为,包括多个无形冰相,如低密度 (LDA) 和高密度 (HDA).
- 最近发现的一种通过球磨加工产生的中密度无形冰 (MDA) 阶段,增加了这种复杂性.
- 尚不完全了解MDA的精确性质和形成路径,以及它与其他无形水态的关系.
研究的目的:
- 通过分子模拟,研究中密度无形冰 (MDA) 的形成和特性.
- 探索剪切在创造新型无形冰相中的作用.
- 了解剪切驱动无形冰 (SDA) 和其他无形水态之间的关系.
主要方法:
- 在受控的压力和剪切速度下,在77K的分子动力学模拟.
- 通过切割冰I,LDA和HDA产生和表征无形冰阶段.
- 对模拟无形冰的密度,度和结构性质的分析.
主要成果:
- 剪切驱动的无形冰 (SDA) 可以由冰I,LDA或HDA在77K的剪切下形成.
- 剪切率的增加会产生SDA,其密度从LDA到HDA不等.
- 高切割速率 (~10^8 s^-1) 产生模仿过度灭环境液态水特性的SDA.
结论:
- 切割速率在水的非平衡相位图中起到关键变量的作用,使其能够进入独特的无形状态.
- 剪切产生的SDA是一种创造无形冰相的可行方法,有可能避免在球磨加工中看到的结晶问题.
- 在高切割速率下生成的SDA是环境液态水难以捉摸的"真玻璃"的优秀实验近似.
相关概念视频
Phase Diagrams
39.8K
A phase diagram combines plots of pressure versus temperature for the liquid-gas, solid-liquid, and solid-gas phase-transition equilibria of a substance. These diagrams indicate the physical states that exist under specific conditions of pressure and temperature and also provide the pressure dependence of the phase-transition temperatures (melting points, sublimation points, boiling points). Regions or areas labeled solid, liquid, and gas represent single phases, while lines or curves represent...
39.8K
Phase Transitions: Melting and Freezing
12.3K
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
12.3K
Phase Diagram
5.8K
The phase of a given substance depends on the pressure and temperature. Thus, plots of pressure versus temperature showing the phase in each region provide considerable insights into the thermal properties of substances. Such plots are known as phase diagrams. For instance, in the phase diagram for water (Figure 1), the solid curve boundaries between the phases indicate phase transitions (i.e., temperatures and pressures at which the phases coexist).
5.8K
States of Water
50.5K
Water exists in any one of the three classical states: solid (ice), liquid (water), and gas (steam or water vapor). The state of water depends on i) the intermolecular forces that draw molecules together and ii) the kinetic energy that leads to movements that pull them apart.
Water freezes when the intermolecular forces are greater than the kinetic energy. Unlike most other substances, water is less dense in its solid state than in its liquid state. This is because each water molecule can form...
Water freezes when the intermolecular forces are greater than the kinetic energy. Unlike most other substances, water is less dense in its solid state than in its liquid state. This is because each water molecule can form...
50.5K
Classifying Matter by State
73.5K
Chemistry is the study of matter and the changes it undergoes. Matter is anything that has mass and occupies space. Matter is all around us; the air, water, soil, mountains, even our bodies are all examples of matter. Matter is divided into three states — solid, liquid, and gas — that are commonly found on earth. The fourth state of matter, plasma, occurs naturally in the interiors of stars.
73.5K
Heating and Cooling Curves
22.5K
When a substance—isolated from its environment—is subjected to heat changes, corresponding changes in temperature and phase of the substance is observed; this is graphically represented by heating and cooling curves.
For instance, the addition of heat raises the temperature of a solid; the amount of heat absorbed depends on the heat capacity of the solid (q = mcsolidΔT). According to thermochemistry, the relation between the amount of heat absorbed or released by a substance, q, and its...
For instance, the addition of heat raises the temperature of a solid; the amount of heat absorbed depends on the heat capacity of the solid (q = mcsolidΔT). According to thermochemistry, the relation between the amount of heat absorbed or released by a substance, q, and its...
22.5K


