Local Atomic Strain in ZnSe(1-x)Te(x) from High Real Space Resolution Neutron Pair Distribution Function Measurements

TL;DR

This study uses high-resolution neutron pair distribution functions to analyze local atomic strains in ZnSe(1-x)Te(x) alloys, revealing detailed bond-length evolution and strain accommodation mechanisms.

Contribution

It provides the first detailed local atomic-scale analysis of bond-lengths and strain in ZnSe(1-x)Te(x) alloys using neutron PDFs with no adjustable parameters.

Findings

Distinct Zn-Se and Zn-Te bonds are resolved and their lengths evolve with composition.

Most alloy strain is accommodated by bond-bending forces rather than bond-length changes.

The Kirkwood potential model accurately fits the experimental PDFs across all compositions.

Abstract

High real-space resolution atomic pair distribution functions (PDFs) have been obtained from ZnSe(1-x)Te(x) using neutron powder diffraction. Distinct Zn-Se and Zn-Te nearest neighbor (nn) bonds, differing in length by delta_r= 0.14Angstroms, are resolved in the measured PDF allowing the evolution with composition of the individual bond-lengths to be studied. The local bond-lengths change much more slowly with doping than the average bond-length obtained crystallographically. The nn bond-length distributions are constant with doping but higher-neighbor pair distributions broaden significantly indicating that most of the strain from the alloying is accommodated by bond-bending forces in the alloy. The PDFs of alloys across the whole doping range are well fit using a model based on the Kirkwood potential. The resulting PDFs give excellent agreement with the measured PDFs over the entire alloy range with no adjustable parameters.