What is the real driving force of bilayer ion beam mixing?

P. Süle, M. Menyhárd, K. Nordlund

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Molecular dynamics simulations have been used to study the driving force of ion irradiation induced interfacial mixing in metal bilayers in which the relative mass difference of the constituents is considerable. We find no apparent effect of chemical forces, such as heat of mixing or cohesive energy up to 7keV ion energy, although a considerable number of liquid and high energy particles (hot atoms) persist up to even 20 ps during the thermal spike. This result is in direct conflict with the widely accepted theory of thermal spike mixing (chemical interdiffusion model). Instead we point out the decisive role of hot (energetic) particles in ion beam mixing of bilayers. The supersaturation of vacancies also occurs, which induces a thermally activated intermixing of the lighter constituent of the bilayer. The delay and the decoupling of the intermixing of the light and heavy constituents is explained as a backscattering effect at the interface: the interface acts as a diffusional barrier for high energy light particles. The heavier atoms are predominantly ejected to the overlayer at the beginning of the thermal spike while the light atoms are injected to the bulk at the beginning of the cooling period (in Ti/Pt) or during the thermal spike with some time delay (Al/Pt). We explain ion induced amorphization by the sufficiently high concentration of energetic (hot) atoms in Al/Pt.

Original languageEnglish
Pages (from-to)517-530
Number of pages14
JournalNuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
Volume226
Issue number4
DOIs
Publication statusPublished - Dec 2004

Fingerprint

spikes
Ion beams
ion beams
hot atoms
Atoms
Ions
energetic particles
supersaturation
ion irradiation
particle energy
decoupling
Amorphization
Supersaturation
atoms
energy
Backscattering
backscattering
Ion bombardment
ions
time lag

Keywords

  • Amorphization
  • Atomic migration
  • Computer simulations
  • Interfacial mixing
  • Ion-beam mixing
  • Ion-solid interaction
  • Mass effect
  • Molecular dynamics

ASJC Scopus subject areas

  • Surfaces, Coatings and Films
  • Instrumentation
  • Surfaces and Interfaces

Cite this

@article{e3f24bc3bb424b598aedb2e227894056,
title = "What is the real driving force of bilayer ion beam mixing?",
abstract = "Molecular dynamics simulations have been used to study the driving force of ion irradiation induced interfacial mixing in metal bilayers in which the relative mass difference of the constituents is considerable. We find no apparent effect of chemical forces, such as heat of mixing or cohesive energy up to 7keV ion energy, although a considerable number of liquid and high energy particles (hot atoms) persist up to even 20 ps during the thermal spike. This result is in direct conflict with the widely accepted theory of thermal spike mixing (chemical interdiffusion model). Instead we point out the decisive role of hot (energetic) particles in ion beam mixing of bilayers. The supersaturation of vacancies also occurs, which induces a thermally activated intermixing of the lighter constituent of the bilayer. The delay and the decoupling of the intermixing of the light and heavy constituents is explained as a backscattering effect at the interface: the interface acts as a diffusional barrier for high energy light particles. The heavier atoms are predominantly ejected to the overlayer at the beginning of the thermal spike while the light atoms are injected to the bulk at the beginning of the cooling period (in Ti/Pt) or during the thermal spike with some time delay (Al/Pt). We explain ion induced amorphization by the sufficiently high concentration of energetic (hot) atoms in Al/Pt.",
keywords = "Amorphization, Atomic migration, Computer simulations, Interfacial mixing, Ion-beam mixing, Ion-solid interaction, Mass effect, Molecular dynamics",
author = "P. S{\"u}le and M. Menyh{\'a}rd and K. Nordlund",
year = "2004",
month = "12",
doi = "10.1016/j.nimb.2004.08.011",
language = "English",
volume = "226",
pages = "517--530",
journal = "Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms",
issn = "0168-583X",
publisher = "Elsevier",
number = "4",

}

TY - JOUR

T1 - What is the real driving force of bilayer ion beam mixing?

AU - Süle, P.

AU - Menyhárd, M.

AU - Nordlund, K.

PY - 2004/12

Y1 - 2004/12

N2 - Molecular dynamics simulations have been used to study the driving force of ion irradiation induced interfacial mixing in metal bilayers in which the relative mass difference of the constituents is considerable. We find no apparent effect of chemical forces, such as heat of mixing or cohesive energy up to 7keV ion energy, although a considerable number of liquid and high energy particles (hot atoms) persist up to even 20 ps during the thermal spike. This result is in direct conflict with the widely accepted theory of thermal spike mixing (chemical interdiffusion model). Instead we point out the decisive role of hot (energetic) particles in ion beam mixing of bilayers. The supersaturation of vacancies also occurs, which induces a thermally activated intermixing of the lighter constituent of the bilayer. The delay and the decoupling of the intermixing of the light and heavy constituents is explained as a backscattering effect at the interface: the interface acts as a diffusional barrier for high energy light particles. The heavier atoms are predominantly ejected to the overlayer at the beginning of the thermal spike while the light atoms are injected to the bulk at the beginning of the cooling period (in Ti/Pt) or during the thermal spike with some time delay (Al/Pt). We explain ion induced amorphization by the sufficiently high concentration of energetic (hot) atoms in Al/Pt.

AB - Molecular dynamics simulations have been used to study the driving force of ion irradiation induced interfacial mixing in metal bilayers in which the relative mass difference of the constituents is considerable. We find no apparent effect of chemical forces, such as heat of mixing or cohesive energy up to 7keV ion energy, although a considerable number of liquid and high energy particles (hot atoms) persist up to even 20 ps during the thermal spike. This result is in direct conflict with the widely accepted theory of thermal spike mixing (chemical interdiffusion model). Instead we point out the decisive role of hot (energetic) particles in ion beam mixing of bilayers. The supersaturation of vacancies also occurs, which induces a thermally activated intermixing of the lighter constituent of the bilayer. The delay and the decoupling of the intermixing of the light and heavy constituents is explained as a backscattering effect at the interface: the interface acts as a diffusional barrier for high energy light particles. The heavier atoms are predominantly ejected to the overlayer at the beginning of the thermal spike while the light atoms are injected to the bulk at the beginning of the cooling period (in Ti/Pt) or during the thermal spike with some time delay (Al/Pt). We explain ion induced amorphization by the sufficiently high concentration of energetic (hot) atoms in Al/Pt.

KW - Amorphization

KW - Atomic migration

KW - Computer simulations

KW - Interfacial mixing

KW - Ion-beam mixing

KW - Ion-solid interaction

KW - Mass effect

KW - Molecular dynamics

UR - http://www.scopus.com/inward/record.url?scp=9544255713&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=9544255713&partnerID=8YFLogxK

U2 - 10.1016/j.nimb.2004.08.011

DO - 10.1016/j.nimb.2004.08.011

M3 - Article

AN - SCOPUS:9544255713

VL - 226

SP - 517

EP - 530

JO - Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

JF - Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

SN - 0168-583X

IS - 4

ER -