First principles investigation on anomalous lattice shrinkage of W alloyed rock salt GeTe

TL;DR

This study uses first-principles calculations to reveal an unexpected lattice shrinkage in W-doped rock salt GeTe, challenging Vegard's law and highlighting the role of electronegativity differences in structural behavior.

Contribution

It provides new insights into the structural properties of ternary solid solutions by explaining anomalous lattice contraction through electronegativity effects.

Findings

W doping causes lattice shrinkage contrary to Vegard's law.

Electronegativity differences lead to shorter W-Te bonds.

Local distortions around W dopants are observed.

Abstract

According to Vegard's law, larger radius atoms substitute for smaller atoms in a solid solution would enlarge the lattice parameters. However, by first-principles calculations, we have observed unusual lattice shrinkage when W replaces Ge in rock salt GeTe. We attribute this anomalous contract to the larger electronegativity difference between W and Te than between Ge and Te, which results in shorter W-Te bonds and pronounced local distortion around W dopants. The present work would provide new insight into the lattice parameter determination and a deeper understanding of the structural properties of ternary solid solutions.