通过古典密度函数式方法在深度超冷下形成模式.
Kun Wang1, Wenjin Chen1, Shifang Xiao2
1College of Materials Science and Engineering, Hunan University, Changsha 410082, China.
Entropy (Basel, Switzerland)
|May 27, 2023
概括
我们使用新的相场晶体模型在超冷液体中探索了晶体的生长. 这个模型准确地预测了各种固化模式,并揭示了由弹性相互作用驱动的微观的柱状到平衡过渡.
科学领域:
- 材料科学 材料科学 材料科学
- 凝聚物质物理学 凝聚物质物理学
- 晶体学 晶体学是指结晶学.
背景情况:
- 不平衡结晶产生了自然和技术中的关键微观结构.
- 了解深度超冷液体中的原子级晶体生长是必不可少的.
研究的目的:
- 研究深度超冷液体中的晶体生长动态.
- 开发和验证一种用于不平衡结晶的新型计算模型.
主要方法:
- 采用了基于密度函数的经典方法.
- 采用复杂的振幅扩展相场晶体 (APFC) 模型,结合空位不平衡效应.
- 模拟原子级晶体生长过程.
主要成果:
- 拟议的APFC模型成功地复制了生长前核 (GFN) 和诸如树突和球状岩石等多样化的模式.
- 发现了一种微观的依赖于种子特征的柱状到平衡过渡,归因于弹性相互作用.
- 确定了两个生长阶段:扩散控制和GFN主导,后者显示出显著的晶格缺陷增量.
结论:
- 具有空位不平衡效应的APFC模型为研究复杂的固化现象提供了强大的框架.
- 暴露的柱状到平轴过渡提供了对微观结构形成的新见解.
- 在GFN主导的生长过程中产生格子缺陷解释了无形核化前体.
相关概念视频
Phase Transitions: Melting and Freezing
12.5K
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...
12.5K
Phase Transitions: Sublimation and Deposition
17.3K
Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to gradually disappear without ever forming any liquid. Snow and ice sublimate at temperatures below the melting point of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high altitudes. When solid iodine is warmed, the solid sublimes...
17.3K
Crystal Field Theory - Octahedral Complexes
26.9K
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
26.9K
Phase Transitions: Vaporization and Condensation
17.7K
The physical form of a substance changes on changing its temperature. For example, raising the temperature of a liquid causes the liquid to vaporize (convert into vapor). The process is called vaporization—a surface phenomenon. Vaporization occurs when the thermal motion of the molecules overcome the intermolecular forces, and the molecules (at the surface) escape into the gaseous state. When a liquid vaporizes in a closed container, gas molecules cannot escape. As these gas phase...
17.7K
Molecular and Ionic Solids
17.3K
Crystalline solids are divided into four types: molecular, ionic, metallic, and covalent network based on the type of constituent units and their interparticle interactions.
Molecular Solids
Molecular crystalline solids, such as ice, sucrose (table sugar), and iodine, are solids that are composed of neutral molecules as their constituent units. These molecules are held together by weak intermolecular forces such as London dispersion forces, dipole-dipole interactions, or hydrogen bonds, which...
Molecular Solids
Molecular crystalline solids, such as ice, sucrose (table sugar), and iodine, are solids that are composed of neutral molecules as their constituent units. These molecules are held together by weak intermolecular forces such as London dispersion forces, dipole-dipole interactions, or hydrogen bonds, which...
17.3K
Thermodynamic Potentials
885
Thermodynamic potentials are state functions that are extremely useful in analyzing a thermodynamic system. They have dimensions of energy. The four important thermodynamic potentials are internal energy, enthalpy, Helmholtz free energy, and Gibbs free energy. These thermodynamic potentials can be expressed using two of the following variables: pressure, volume, temperature, and entropy. These two variables are expressed as the rate of change of the thermodynamic potential with respect to other...
885


