Negative thermal expansion in ZnF$_2$

TL;DR

This paper reports the discovery of negative thermal expansion in ZnF₂ at low temperatures through neutron diffraction and supports the findings with first-principles calculations that qualitatively match the experimental data.

Contribution

It provides the first experimental observation of NTE in ZnF₂ and combines it with theoretical calculations to explain the phenomenon.

Findings

NTE observed at low temperatures in ZnF₂

First-principles calculations reproduce experimental volume dependence

Provides insight into NTE mechanisms in simple compounds

Abstract

We have investigated temperature dependence of the lattice parameters and the unit cell volume of ZnF$_2$ by neutron diffraction and have discovered negative thermal expansion (NTE) at low temperature. To understand why this simple compound exhibits NTE we performed first principle calculations. These calculations reproduce qualitatively the experimental temperature dependence of volume.