Modeling of Diffusivity for 2D Vacancy Nanopits and Comparison with 2D Adatom Nanoislands on Metal(100) Surfaces Including Analysis for Ag(100)

Lai, King C.; Liu, Da-Jiang; Thiel, Patricia A.; Evans, James W.

doi:10.1021/acs.jpcc.7b12527

Title: Modeling of Diffusivity for 2D Vacancy Nanopits and Comparison with 2D Adatom Nanoislands on Metal(100) Surfaces Including Analysis for Ag(100)

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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 lattice-gas 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(10²) ≤ N ≤ O(10³). Monotonic decay, D_N~ N^-β, is found for N ≥ O(10²) 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 compare predictions from our model incorporating appropriate energetic parameters for Ag(100) with differentmore »« less

Authors:

Lai, King C. ^[1]; Liu, Da-Jiang ^[2]; Thiel, Patricia A. ^[3]; Evans, James W. ^[4]

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:: 2018-02-22

Research Org.:: Ames Lab., Ames, IA (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)

OSTI Identifier:: 1422773

Report Number(s):: IS-J-9530
Journal ID: ISSN 1932-7447; TRN: US1801661

Grant/Contract Number:: AC02-07CH11358; CHE-1507223

Resource Type:: Accepted Manuscript

Journal Name:: Journal of Physical Chemistry. C

Additional Journal Information:: Journal Volume: 122; Journal Issue: 21; Journal ID: ISSN 1932-7447

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, Da-Jiang, 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.

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                    Lai, King C., Liu, Da-Jiang, 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.  https://doi.org/10.1021/acs.jpcc.7b12527

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                    Lai, King C., Liu, Da-Jiang, 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.  https://doi.org/10.1021/acs.jpcc.7b12527.  https://www.osti.gov/servlets/purl/1422773.

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@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, Da-Jiang 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 lattice-gas 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~ N-β, 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}

}

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