Camel back shaped Kirkwood-Buff Integrals
Abstract
Some binary mixtures, such as specific alcohol-alkane mixtures, or even water-tbutanol, exhibit two humps camel back shaped KBI. This is in sharp contrast with usual KBI of binary mixtures having a single extremum. This extremum is interpreted as the region of maximum concentration fluctuations, and usually occurs in binary mixtures presenting appreciable micro-segregation, and corresponds to where the mixture exhibit a percolation of the two species domains. In this paper, it is shown that two extrema occur in binary mixtures when one species forms "meta-particle" aggregates, the latter which act as a meta-species, and have their own concentration fluctuations, hence their own KBI extremum. This "meta-extremum" occurs at low concentration of the aggregate-forming species (such as alcohol in alkane), and is independant of the other usual extremum observed at mid volume fraction occupancy. These systems are a good illustration of the concept of the duality between concentration fluctuations and micro-segregation.
Cite
@article{arxiv.2201.02406,
title = {Camel back shaped Kirkwood-Buff Integrals},
author = {Aurélien Perera and Martina Požar and Bernarda Lovrinčević},
journal= {arXiv preprint arXiv:2201.02406},
year = {2022}
}