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

Journal Article · · Journal of Physical Chemistry. C
 [1];  [2];  [3];  [4]
  1. Iowa State Univ., Ames, IA (United States). Dept. of Physics & Astronomy
  2. Ames Lab. and Iowa State Univ., Ames, IA (United States)
  3. Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Chemistry, and Dept. of Materials Science & Engineering
  4. Iowa State Univ., Ames, IA (United States). Dept. of Physics & Astronomy, and Dept. of Mathematics
+ Show Author Affiliations

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.

Research Organization:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)
Grant/Contract Number:
AC02-07CH11358; CHE-1507223
OSTI ID:
1422773
Report Number(s):
IS-J-9530; TRN: US1801661
Journal Information:
Journal of Physical Chemistry. C, Vol. 122, Issue 21; ISSN 1932-7447
Publisher:
American Chemical SocietyCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 3 works
Citation information provided by
Web of Science

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