In studying solidification process by simulations on the atomic scale, the modeling of crystal nucleation or amorphization requires the construction of interatomic interactions that are able to reproduce the properties of both the solid and the liquid states. Taking into account rare nucleation events or structural relaxation under deep undercooling conditions requires much larger length scales and longer time scales than those achievable bymolecular dynamics (AIMD). This problem is addressed by means of classical molecular dynamics simulations using a well established high dimensional neural network potential trained on a set of configurations generated by AIMD relevant for solidification phenomena. Our dataset contains various crystalline structures and liquid states at different pressures, including their time fluctuations in a wide range of temperatures. Applied to elemental aluminium, the resulting potential is shown to be efficient to reproduce the basic structural, dynamics and thermodynamic quantities in the liquid and undercooled states. Early stages of crystallization are further investigated on a much larger scale with one million atoms, allowing us to unravel features of the homogeneous nucleation mechanisms in the fcc phase at ambient pressure as well as in the bcc phase at high pressure with unprecedented accuracy close to theone. In both cases, a single step nucleation process is observed.
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http://dx.doi.org/10.1088/1361-648X/ac9d7d | DOI Listing |
Adv Mater
November 2024
Istituto Italiano di Tecnologia, Via Morego 30, Genova, 16136, Italy.
Perovskite nanocrystal superlattices are being actively studied after reports have emerged on collective excitonic properties at cryogenic temperatures, where energetic disorder is minimized due to the frozen lattice vibrations. However, an important issue related to structural disorder of superlattices at low temperatures has received little attention to date. In this work, it is shown that CsPbBr nanocrystal superlattices undergo a reversible order-disorder transition upon cooling to 90 K.
View Article and Find Full Text PDFCryst Growth Des
October 2024
Department of Mechanical and Civil Engineering, California Institute of Technology, Pasadena, California 91125-0002, United States.
The microstructure of snow determines its fundamental properties such as mechanical strength, reflectivity, or thermo-hydraulic properties. Snow undergoes continuous microstructural changes due to local gradients in temperature, humidity, or curvature, in a process known as snow metamorphism. In this work, we focus on wet snow metamorphism, which occurs when the temperature is close to the melting point and involves phase transitions among liquid water, water vapor, and solid ice.
View Article and Find Full Text PDFInt J Biol Macromol
December 2024
Department of Textiles, Merchandising and Fashion Design, University of Nebraska-Lincoln, Lincoln, NE 68583-0802, United States; Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, NE 68583-0802, United States; Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE 68583-0802, United States. Electronic address:
We report a green, non-destructive, and highly effective extraction, dissolution, film casting and solidification technology for cottonseed proteins from cottonseed meals. Although cottonseed meals are protein-rich, with about 40 % of proteins, they are cheap with a price 20 % to 50 % lower than soybean meals due to their poor performance as feed and bioplastics and due to the limited efforts from the academia and industries. Our green and protective protein extraction technology provided an extraction yield of 89 % and purity of 92 % with minimal destruction to the protein backbones, better than those reported previously.
View Article and Find Full Text PDFPhys Rev E
September 2024
School of Mathematics and Statistics, Huazhong University of Science and Technology, Wuhan 430074, China.
In this paper we first propose a phase-field model for the containerless freezing problems, in which the volume expansion or shrinkage of the liquid caused by the density change during the phase change process is considered by adding a mass source term to the continuum equation. Then a phase-field-based lattice Boltzmann (LB) method is further developed to simulate solid-liquid phase change phenomena in multiphase systems. We test the developed LB method by the problem of conduction-induced freezing in a semi-infinite space, the three-phase Stefan problem, and the droplet solidification on a cold surface, and the numerical results are in agreement with the analytical and experimental solutions.
View Article and Find Full Text PDFSci Rep
October 2024
Division of Mechanical and Biomedical Engineering, Ewha Womans University, Seoul, 03760, Republic of Korea.
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