Phase transitions and ordering of confined dipolar fluids

TL;DR

This study uses a modified mean-field density functional theory to explore phase transitions and local structures of confined dipolar fluids in slit pores, revealing how confinement influences phase behavior and ordering.

Contribution

It introduces a combined approach using Carnahan-Starling and fundamental-measure theories to analyze phase behavior of confined dipolar fluids, including local orientational structures.

Findings

Phase diagrams shift with pore width variations.

Multiple first-order phase transitions identified.

Local ferromagnetic ordering studied in confined geometries.

Abstract

We apply a modified mean-field density functional theory to determine the phase behavior of Stockmayer fluids in slitlike pores formed by two walls with identical substrate potentials. Based on the Carnahan-Starling equation of state, a fundamental-measure theory is employed to incorporate the effects of short-ranged hard sphere - like correlations while the long-ranged contributions to the fluid interaction potential are treated perturbatively. The liquid-vapor, ferromagnetic liquid - vapor, and ferromagnetic liquid - isotropic liquid first-order phase separations are investigated. The local orientational structure of the anisotropic and inhomogeneous ferromagnetic liquid phase is also studied. We discuss how the phase diagrams are shifted and distorted upon varying the pore width.