Charge ordering and self-assembled nanostructures in a fcc Coulomb lattice gas

TL;DR

This study uses a Coulomb lattice gas model and Monte Carlo simulations to explore compositional ordering and nanostructure formation in Ag, Pb, Sb, Te ion systems with NaCl structure, revealing various microstructures and phase behaviors.

Contribution

It introduces a Coulomb lattice gas model on an fcc lattice to analyze ordering in complex chalcogenide systems, providing new insights into their microstructural arrangements.

Findings

Formation of ordered superlattice structures with AgSbTe2 layers

Observation of tubular structures at x=0.5

AgSbTe2 adopts a bct structure at x=1

Abstract

The compositional ordering of Ag, Pb, Sb, Te ions in (AgSbTe$_{2}$)$_{x}$(PbTe)$_{2(1-x)}$ systems possessing a NaCl structure is studied using a Coulomb lattice gas (CLG) model on a face-centered cubic (fcc) lattice and Monte Carlo simulations. Our results show different possible microstructural orderings. Ordered superlattice structures formed out of AgSbTe$_{2}$ layers separated by Pb$_{2}$Te$_{2}$ layers are observed for a large range of $x$ values. For $x=0.5$, we see an array of tubular structures formed by AgSbTe$_{2}$ and Pb$_{2}$Te$_{2}$ blocks. For $x=1$, AgSbTe$_{2}$ has a body-centered tetragonal (bct) structure which is in agreement with previous Monte Carlo simulation results for restricted primitive model (RPM) at closed packed density. The phase diagram of this frustrated CLG system is discussed.