Crystalline-to-Amorphous Phase Transformation in CuO Nanowires for Gaseous Ionization and Sensing Application

ACS Sensors ◽  
2021 ◽  
Author(s):  
Hai Liu ◽  
Haoyu Zhang ◽  
Wenhuan Zhu ◽  
Maolin Bo ◽  
Tingting Zhao
Keyword(s):  
Phase Transformation ◽  
Amorphous Phase ◽  
Cuo Nanowires ◽  
Sensing Application

scholarly journals Effects of temperatures on pressure-induced structural changes in amorphous Si: A molecular-dynamics study

10.29007/6kp3 ◽  
2020 ◽  
Author(s):  
Renji Mukuno ◽  
Manabu Ishimaru
Keyword(s):  
Molecular Dynamics ◽  
Phase Transformation ◽  
Amorphous Phase ◽  
Structural Changes ◽  
Interatomic Potential ◽  
Activation Barrier ◽  
Distribution Functions ◽  
High Density ◽  
Angle Distribution ◽  
Dynamics Simulations

The structural changes of amorphous silicon (a-Si) under compressive pressure were examined by molecular-dynamics simulations using the Tersoff interatomic potential. a-Si prepared by melt-quenching methods was pressurized up to 30 GPa under different temperatures (300K and 500K). The density of a-Si increased from 2.26 to 3.24 g/cm3 with pressure, suggesting the occurrence of the low-density to high-density amorphous phase transformation. This phase transformation occurred at the lower pressure with increasing the temperature because the activation barrier for amorphous-to-amorphous phase transformation could be exceeded by thermal energy. The coordination number increased with pressure and time, and it was saturated at different values depending on the pressure. This suggested the existence of different metastable atomic configurations in a-Si. Atomic pair-distribution functions and bond-angle distribution functions suggested that the short-range ordered structure of high-density a-Si is similar to the structure of the high-pressure phase of crystalline Si (β-tin and Imma structures).

Study on Nanometric Machining Mechanism of Monocrystalline Silicon by Molecular Dynamics

2011 ◽  
Vol 393-395 ◽  
pp. 1475-1478
Author(s):  
Hong Guo
Keyword(s):  
Molecular Dynamics ◽  
Phase Transformation ◽  
Potential Function ◽  
Amorphous Phase ◽  
Cutting Forces ◽  
Elastic Recovery ◽  
Monocrystalline Silicon ◽  
Three Dimensional Model ◽  
Cutting Mechanism ◽  
Nanometric Cutting

A three-dimensional model of molecular dynamics (MD) was employed to study the nanometric cutting mechanism of monocrystalline silicon. The model included the utilization of the Morse potential function to simulate the interatomic force between the workpiece and the tool, and the Tersoff potential function between silicon atoms. Amorphous phase transformation and chip volume change are observed by analyses of the snapshots of the MD simulation of the nanometric cutting process, energy and cutting forces. Dislocations and elastic recovery in the deformed region around the tool do not appear. Cutting forces initiate the amorphous phase transformation, and thrust forces play an important role in driving the further transformation development. Nanometric cutting mechanism of monocrystalline silicon is not the plastic deformation involving the generation and propagation of dislocations, but deformation via amorphous phase transformation.

scholarly journals Deformation-induced crystalline-to-amorphous phase transformation in a CrMnFeCoNi high-entropy alloy

2021 ◽  
Vol 7 (14) ◽  
pp. eabe3105
Author(s):  
Hao Wang ◽  
Dengke Chen ◽  
Xianghai An ◽  
Yin Zhang ◽  
Shijie Sun ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Amorphous Phase ◽  
Structural Evolution ◽  
Crack Tip ◽  
Dislocation Slip ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Dislocation Glide ◽  
Ultrafine Grained

The Cantor high-entropy alloy (HEA) of CrMnFeCoNi is a solid solution with a face-centered cubic structure. While plastic deformation in this alloy is usually dominated by dislocation slip and deformation twinning, our in situ straining transmission electron microscopy (TEM) experiments reveal a crystalline-to-amorphous phase transformation in an ultrafine-grained Cantor alloy. We find that the crack-tip structural evolution involves a sequence of formation of the crystalline, lamellar, spotted, and amorphous patterns, which represent different proportions and organizations of the crystalline and amorphous phases. Such solid-state amorphization stems from both the high lattice friction and high grain boundary resistance to dislocation glide in ultrafine-grained microstructures. The resulting increase of crack-tip dislocation densities promotes the buildup of high stresses for triggering the crystalline-to-amorphous transformation. We also observe the formation of amorphous nanobridges in the crack wake. These amorphization processes dissipate strain energies, thereby providing effective toughening mechanisms for HEAs.

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