Diffusion and Transport Coefficients in Synthetic Opals

TL;DR

This paper models diffusion in synthetic opals, linking their structure to transport properties, and provides methods to estimate diffusion and transport coefficients based on structural parameters.

Contribution

It introduces a theoretical approach to calculate diffusion and transport coefficients in synthetic opals considering their microstructure.

Findings

Diffusion coefficient depends on neck size and carrier mean-free path.

Transport coefficients can be estimated from thermal and electrical conductivity.

Theory applicable to other periodic structures.

Abstract

Opals are structures composed of the closed packing of spheres in the size range of nano-to-micro meter. They are sintered to create small necks at the points of contact. We have solved the diffusion problem in such structures. The relation between the diffusion coefficient and the termal and electrical conductivity makes possible to estimate the transport coefficients of opal structures. We estimate this changes as function of the neck size and the mean-free path of the carriers. The theory presented is also applicable to the diffusion problem in other periodic structures.