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Molecular dynamics investigations of mechanical behaviours in monocrystalline silicon due to nanoindentation at cryogenic temperatures and room temperature.

Du X, Zhao H, Zhang L, Yang Y, Xu H, Fu H, Li L - Sci Rep (2015)

Bottom Line: Molecular dynamics simulations of nanoindentation tests on monocrystalline silicon (010) surface were conducted to investigate the mechanical properties and deformation mechanism from cryogenic temperature being 10 K to room temperature being 300 K.By searching for the presence of the unique non-bonded fifth neighbour atom, the metastable phases (Si-III and Si-XII) with fourfold coordination could be distinguished from Si-I phase during the loading stage of nanoindentation process.The Si-II, Si-XIII, and amorphous phase were also found in the region beneath the indenter.

View Article: PubMed Central - PubMed

Affiliation: School of Mechanical Science and Engineering, Jilin University, Renmin Street 5988, Changchun, Jilin 130025, China.

ABSTRACT
Molecular dynamics simulations of nanoindentation tests on monocrystalline silicon (010) surface were conducted to investigate the mechanical properties and deformation mechanism from cryogenic temperature being 10‚ÄČK to room temperature being 300‚ÄČK. Furthermore, the load-displacement curves were obtained and the phase transformation was investigated at different temperatures. The results show that the phase transformation occurs both at cryogenic temperatures and at room temperature. By searching for the presence of the unique non-bonded fifth neighbour atom, the metastable phases (Si-III and Si-XII) with fourfold coordination could be distinguished from Si-I phase during the loading stage of nanoindentation process. The Si-II, Si-XIII, and amorphous phase were also found in the region beneath the indenter. Moreover, through the degree of alignment of the metastable phases along specific crystal orientation at different temperatures, it was found that the temperature had effect on the anisotropy of the monocrystalline silicon, and the simulation results indicate that the anisotropy of monocrystalline silicon is strengthened at low temperatures.

No MeSH data available.


Related in: MedlinePlus

Lateral and horizontal cross-sectional view of the distribution of the six-coordinated atoms at the maximum indentation depth at different temperatures: (a) 10‚ÄČK, (b) 100‚ÄČK, (c) 200‚ÄČK, (d) 300‚ÄČK.
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f8: Lateral and horizontal cross-sectional view of the distribution of the six-coordinated atoms at the maximum indentation depth at different temperatures: (a) 10‚ÄČK, (b) 100‚ÄČK, (c) 200‚ÄČK, (d) 300‚ÄČK.

Mentions: To analyze the phase transformation from the four-coordinated structure to the six-coordinated structure at different temperatures in more detail, lateral and horizontal cross-sectional views of the distribution of the six-coordinated atoms at the maximum indentation depth are shown in Fig. 8. The phase transformation and phase distribution are different at different temperatures. At a temperature of 10 and 100‚ÄČK, the Si-II phase is formed beneath the indenter in region A (marked with a red circle). The Si-XIII phase, which was firstly found and defined by Mylvaganam et al.36 via MD simulation, is located in region B (marked with a dark circle), aligned along the [100] and [001] direction. Both the Si-II and the Si-XIII phase have six-coordinated atoms. However, the distance to the nearest neighbours is different36, as shown in the enlarged view in Fig. 8. The amorphous phase with six-coordinated atoms is formed between the nearest regions filled with the Si-XIII phase. At a temperature of 200 and 300‚ÄČK, only the Si-II phase and the amorphous phase are formed, and a phase transformation from Si-I to Si-XIII does not occur. The atoms of the six-coordinated amorphous phase (in region C) are distributed around the Si-II phase.


Molecular dynamics investigations of mechanical behaviours in monocrystalline silicon due to nanoindentation at cryogenic temperatures and room temperature.

Du X, Zhao H, Zhang L, Yang Y, Xu H, Fu H, Li L - Sci Rep (2015)

Lateral and horizontal cross-sectional view of the distribution of the six-coordinated atoms at the maximum indentation depth at different temperatures: (a) 10‚ÄČK, (b) 100‚ÄČK, (c) 200‚ÄČK, (d) 300‚ÄČK.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4633730&req=5

f8: Lateral and horizontal cross-sectional view of the distribution of the six-coordinated atoms at the maximum indentation depth at different temperatures: (a) 10‚ÄČK, (b) 100‚ÄČK, (c) 200‚ÄČK, (d) 300‚ÄČK.
Mentions: To analyze the phase transformation from the four-coordinated structure to the six-coordinated structure at different temperatures in more detail, lateral and horizontal cross-sectional views of the distribution of the six-coordinated atoms at the maximum indentation depth are shown in Fig. 8. The phase transformation and phase distribution are different at different temperatures. At a temperature of 10 and 100‚ÄČK, the Si-II phase is formed beneath the indenter in region A (marked with a red circle). The Si-XIII phase, which was firstly found and defined by Mylvaganam et al.36 via MD simulation, is located in region B (marked with a dark circle), aligned along the [100] and [001] direction. Both the Si-II and the Si-XIII phase have six-coordinated atoms. However, the distance to the nearest neighbours is different36, as shown in the enlarged view in Fig. 8. The amorphous phase with six-coordinated atoms is formed between the nearest regions filled with the Si-XIII phase. At a temperature of 200 and 300‚ÄČK, only the Si-II phase and the amorphous phase are formed, and a phase transformation from Si-I to Si-XIII does not occur. The atoms of the six-coordinated amorphous phase (in region C) are distributed around the Si-II phase.

Bottom Line: Molecular dynamics simulations of nanoindentation tests on monocrystalline silicon (010) surface were conducted to investigate the mechanical properties and deformation mechanism from cryogenic temperature being 10 K to room temperature being 300 K.By searching for the presence of the unique non-bonded fifth neighbour atom, the metastable phases (Si-III and Si-XII) with fourfold coordination could be distinguished from Si-I phase during the loading stage of nanoindentation process.The Si-II, Si-XIII, and amorphous phase were also found in the region beneath the indenter.

View Article: PubMed Central - PubMed

Affiliation: School of Mechanical Science and Engineering, Jilin University, Renmin Street 5988, Changchun, Jilin 130025, China.

ABSTRACT
Molecular dynamics simulations of nanoindentation tests on monocrystalline silicon (010) surface were conducted to investigate the mechanical properties and deformation mechanism from cryogenic temperature being 10‚ÄČK to room temperature being 300‚ÄČK. Furthermore, the load-displacement curves were obtained and the phase transformation was investigated at different temperatures. The results show that the phase transformation occurs both at cryogenic temperatures and at room temperature. By searching for the presence of the unique non-bonded fifth neighbour atom, the metastable phases (Si-III and Si-XII) with fourfold coordination could be distinguished from Si-I phase during the loading stage of nanoindentation process. The Si-II, Si-XIII, and amorphous phase were also found in the region beneath the indenter. Moreover, through the degree of alignment of the metastable phases along specific crystal orientation at different temperatures, it was found that the temperature had effect on the anisotropy of the monocrystalline silicon, and the simulation results indicate that the anisotropy of monocrystalline silicon is strengthened at low temperatures.

No MeSH data available.


Related in: MedlinePlus