Direct interpretation of the X-ray and neutron 3D-$\Delta$PDFs of yittria stabilized zirconia

TL;DR

This study uses 3D-$ riangle$PDF analysis from X-ray and neutron diffraction to reveal atomic shifts and vacancy clustering in yttria stabilized zirconia, providing direct insight into its local structure.

Contribution

It presents a quantitative interpretation of 3D-$ riangle$PDFs to directly observe atomic displacements and vacancy arrangements in yttria stabilized zirconia.

Findings

Oxygen ions shift by 0.515 Å towards vacancies.

Metal ions shift by 0.269 Å away from vacancies.

Vacancies tend to cluster along specific directions, leading to 6-fold coordination.

Abstract

Three dimensional difference pair distribution functions from X-ray and neutron diffraction experiments are reported for yttria stabilized zirconia (Zr$_{0.82}$Y$_{0.18}$O$_{1.91}$). We use a quantitative analysis of the signatures in the 3D-$\Delta$PDFs to establish that oxygen ions neighbouring a vacancy shift by 0.515(5)~\AA\ along $\langle 1,0,0 \rangle$ towards the vacancy while metal ions neighbouring a vacancy shift by 0.269(2)~\AA\ along $\langle 1,1,1 \rangle$ away from the vacancy. The neutron 3D-$\Delta$PDF shows a tendency for vacancies to cluster along $\langle \frac{1}{2},\frac{1}{2},\frac{1}{2}\rangle$, which results in 6-fold coordinated metal ions.