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Establishing simulations of shockwaves in InSb using molecular dynamics

Löfquist, Erik LU (2021) In Lund reports on atomic physics (LRAP) PHYM01 20211
Atomic Physics
Department of Physics
Abstract
Laser induced shockwaves have previously been shown to prompt structural changes in germanium. Similar experiments have now been performed in InSb, with powder diffraction patterns displaying a peak at 2.3Å indicating the formation of an unknown structure. In this work, large scale molecular dynamics simulations of shockwave propagation in germanium and InSb are presented. The results are in excellent agreement with published simulations in germanium, and further corroborate the experimental powder diffraction pattern in InSb. Possible structural explanations to the 2.3Å peak are discussed, with the formation of wurtzite InSb being unsupported. Desirable future enhancements to the model accuracy and efficiency are presented.
Popular Abstract
Simulating shockwaves atom by atom

Sending shockwaves into materials can permanently alter their structure. Uncovering the secrets of this process on the atomistic scale paves the way towards the materials of the future.

Under pressure, a lot can change. Even materials start to behave differently. At sufficiently high pressures, new materials can form. New materials are always interesting in engineering. They can both improve existing devices as well as enable completely new ones. Materials under pressure is also interesting for fundamental science. Knowing how such materials behave can give insight into for instance mineral formation.

One way to reach high pressures in materials is to send a shockwave through them. Shockwaves... (More)
Simulating shockwaves atom by atom

Sending shockwaves into materials can permanently alter their structure. Uncovering the secrets of this process on the atomistic scale paves the way towards the materials of the future.

Under pressure, a lot can change. Even materials start to behave differently. At sufficiently high pressures, new materials can form. New materials are always interesting in engineering. They can both improve existing devices as well as enable completely new ones. Materials under pressure is also interesting for fundamental science. Knowing how such materials behave can give insight into for instance mineral formation.

One way to reach high pressures in materials is to send a shockwave through them. Shockwaves are waves travelling faster than the speed of sound. They arise when something moves very fast in a medium. The most familiar example of a shockwave is the sonic boom created when an airplane travels very fast in air.

Shockwaves can be sent into materials by shining laser light on them. This causes the material to heat up, melt, and rapidly expand. The expansion can happen so fast that a shockwave is created. By then sending X-rays into the material and seeing how they reflect, part of the structure can be discerned.

An experiment like this has been performed in a material called indium antimonide. After the shockwave passed, a new mysterious X-ray reflection appeared. A new material structure formed! But to know exactly what this structure is, other methods than studying X-ray reflections are required.
A possible method is to simulate the shockwave in a computer, atom by atom. Such simulations are called molecular dynamics. They require many computers to work together to simulate millions of atoms simultaneously. This thesis is a molecular dynamics simulation of shockwaves in indium antimonide. It can potentially be used to explain what happens in the material as the shockwave progresses. Does for instance the mysterious X-ray reflection appear?

Indeed it does! The simulations confirm that the mysterious X-ray reflection should appear. Its origin is however yet to be determined. Close examination of the atom positions in the simulation should be able to reveal what material structure formed. If the material turns out to be useful, further molecular dynamics simulations could be used to for instance see how the material can be produced efficiently. (Less)
Please use this url to cite or link to this publication:
author
Löfquist, Erik LU
supervisor
organization
course
PHYM01 20211
year
type
H2 - Master's Degree (Two Years)
subject
publication/series
Lund reports on atomic physics (LRAP)
report number
571
language
English
id
9060962
date added to LUP
2021-07-26 12:46:47
date last changed
2021-07-26 12:46:47
@misc{9060962,
  abstract     = {{Laser induced shockwaves have previously been shown to prompt structural changes in germanium. Similar experiments have now been performed in InSb, with powder diffraction patterns displaying a peak at 2.3Å indicating the formation of an unknown structure. In this work, large scale molecular dynamics simulations of shockwave propagation in germanium and InSb are presented. The results are in excellent agreement with published simulations in germanium, and further corroborate the experimental powder diffraction pattern in InSb. Possible structural explanations to the 2.3Å peak are discussed, with the formation of wurtzite InSb being unsupported. Desirable future enhancements to the model accuracy and efficiency are presented.}},
  author       = {{Löfquist, Erik}},
  language     = {{eng}},
  note         = {{Student Paper}},
  series       = {{Lund reports on atomic physics (LRAP)}},
  title        = {{Establishing simulations of shockwaves in InSb using molecular dynamics}},
  year         = {{2021}},
}