Modeling of Diffusivity for 2D Vacancy Nanopits and Comparison with 2D Adatom Nanoislands on Metal(100) Surfaces Including Analysis for Ag(100)
Abstract
Diffusion coefficients, D _{N}, for 2D vacancy nanopits are compared with those for 2D homoepitaxial adatom nanoislands on metal(100) surfaces, focusing on the variation of DN with size, N. Here, N is measured in missing atoms for pits and adatoms for islands. Analysis of D _{N} is based on kinetic Monte Carlo simulations of a tailored stochastic latticegas model, where pit and island diffusion are mediated by periphery diffusion, i.e., by edge atom hopping. Precise determination of D _{N} versus N for typical parameters reveals a cyclical variation with an overall decrease in magnitude for increasing moderate O(10 ^{2}) ≤ N ≤ O(10 ^{3}). Monotonic decay, D _{N}~ N ^{β}, is found for N ≥ O(10 ^{2}) with effective exponents, β = β _{eff}, for both pits and islands, both well below the macroscopic value of βmacro = 3/2. D _{N} values for vacancy pits are significantly lower (higher) than for adatom islands for moderate N in the case of low (high) kink rounding barrier. However, D _{N} values for pits and islands slowly merge, and β _{eff} → 3/2 for sufficiently large N. The latter feature is expected from continuum Langevin formulations appropriate for large sizes. Finally, we comparemore »
 Authors:

 Iowa State Univ., Ames, IA (United States). Dept. of Physics & Astronomy
 Ames Lab. and Iowa State Univ., Ames, IA (United States)
 Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Chemistry, and Dept. of Materials Science & Engineering
 Iowa State Univ., Ames, IA (United States). Dept. of Physics & Astronomy, and Dept. of Mathematics
 Publication Date:
 Research Org.:
 Ames Laboratory (AMES), Ames, IA (United States)
 Sponsoring Org.:
 USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC22); National Science Foundation (NSF)
 OSTI Identifier:
 1422773
 Report Number(s):
 ISJ9530
Journal ID: ISSN 19327447; TRN: US1801661
 Grant/Contract Number:
 AC0207CH11358; CHE1507223
 Resource Type:
 Accepted Manuscript
 Journal Name:
 Journal of Physical Chemistry. C
 Additional Journal Information:
 Journal Volume: 122; Journal Issue: 21; Journal ID: ISSN 19327447
 Publisher:
 American Chemical Society
 Country of Publication:
 United States
 Language:
 English
 Subject:
 36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Citation Formats
Lai, King C., Liu, DaJiang, Thiel, Patricia A., and Evans, James W. Modeling of Diffusivity for 2D Vacancy Nanopits and Comparison with 2D Adatom Nanoislands on Metal(100) Surfaces Including Analysis for Ag(100). United States: N. p., 2018.
Web. doi:10.1021/acs.jpcc.7b12527.
Lai, King C., Liu, DaJiang, Thiel, Patricia A., & Evans, James W. Modeling of Diffusivity for 2D Vacancy Nanopits and Comparison with 2D Adatom Nanoislands on Metal(100) Surfaces Including Analysis for Ag(100). United States. doi:10.1021/acs.jpcc.7b12527.
Lai, King C., Liu, DaJiang, Thiel, Patricia A., and Evans, James W. Thu .
"Modeling of Diffusivity for 2D Vacancy Nanopits and Comparison with 2D Adatom Nanoislands on Metal(100) Surfaces Including Analysis for Ag(100)". United States. doi:10.1021/acs.jpcc.7b12527. https://www.osti.gov/servlets/purl/1422773.
@article{osti_1422773,
title = {Modeling of Diffusivity for 2D Vacancy Nanopits and Comparison with 2D Adatom Nanoislands on Metal(100) Surfaces Including Analysis for Ag(100)},
author = {Lai, King C. and Liu, DaJiang and Thiel, Patricia A. and Evans, James W.},
abstractNote = {Diffusion coefficients, DN, for 2D vacancy nanopits are compared with those for 2D homoepitaxial adatom nanoislands on metal(100) surfaces, focusing on the variation of DN with size, N. Here, N is measured in missing atoms for pits and adatoms for islands. Analysis of DN is based on kinetic Monte Carlo simulations of a tailored stochastic latticegas model, where pit and island diffusion are mediated by periphery diffusion, i.e., by edge atom hopping. Precise determination of DN versus N for typical parameters reveals a cyclical variation with an overall decrease in magnitude for increasing moderate O(102) ≤ N ≤ O(103). Monotonic decay, DN~ Nβ, is found for N ≥ O(102) with effective exponents, β = βeff, for both pits and islands, both well below the macroscopic value of βmacro = 3/2. DN values for vacancy pits are significantly lower (higher) than for adatom islands for moderate N in the case of low (high) kink rounding barrier. However, DN values for pits and islands slowly merge, and βeff → 3/2 for sufficiently large N. The latter feature is expected from continuum Langevin formulations appropriate for large sizes. Finally, we compare predictions from our model incorporating appropriate energetic parameters for Ag(100) with different sets of experimental data for diffusivity at 300 K, including assessment of βeff, for experimentally observed sizes N from ~100 to ~1000.},
doi = {10.1021/acs.jpcc.7b12527},
journal = {Journal of Physical Chemistry. C},
number = 21,
volume = 122,
place = {United States},
year = {2018},
month = {2}
}
Web of Science