On the mechanism of negative compressibility in layered compounds

TL;DR

This paper presents a simple model explaining negative compressibility in layered compounds under pressure, highlighting the role of fluid interactions and analyzing recent experimental data on graphite oxide.

Contribution

It introduces a theoretical mechanism for negative compressibility involving fluid-matrix interactions and applies it to interpret experimental observations.

Findings

Non-monotonic interlayer spacing behavior under pressure

Competition between applied and internal fluid-induced pressure

Analysis of graphite oxide 'structure breathing' phenomena

Abstract

A mechanism of negative compressibility occurring in compressed layered compounds in the presence of a pressure transmitting fluid medium is discussed within a simple model. It takes into account the excluded volume effects and soft fluid-matrix repulsion. It is demonstrated that a non-monotonic behavior of the interlayer spacing with the applied pressure results from a competition between the applied pressure and the internal one induced by the adsorbed fluid. Recent experimental data on the graphite oxide "structure breathing" under compression in the presence of water are analyzed in the light of these theoretical results.