We study experimentally how gaseous HCl and NH_3 diffuse from opposite sides of and react in silica aerogel rods with porosity of 92 % and average pore size of about 50 nm. The reaction leads to solid NH_4Cl, which is deposited in thin sheet-like structures. We present a numerical study of the phenomenon. Due to the difference in boundary conditions between this system and those usually studied, we find the sheet-like structures in the aerogel to differ significantly from older studies. The influence of random nucleation centers and inhomogeneities in the aerogel is studied numerically.
@article{arxiv.cond-mat/9706186,
title = {Band Formation during Gaseous Diffusion in Aerogels},
author = {M. A. Einarsrud and F. A. Maao and A. Hansen and M. Kirkedelen and J. Samseth},
journal= {arXiv preprint arXiv:cond-mat/9706186},
year = {2009}
}
Comments
7 pages RevTex and 8 figures. Figs. 4-8 in Postscript, Figs. 1-3 on request from authors