The study of high pressure structural stability of CeO2 nanoparticles

TL;DR

This study investigates how CeO2 nanoparticles of different sizes respond to high pressure, revealing that smaller particles are more stable under quasihydrostatic conditions but sensitive to experimental conditions and grain size effects.

Contribution

It provides new insights into the size-dependent high pressure stability of CeO2 nanoparticles and the influence of experimental conditions on their phase transitions.

Findings

12 nm CeO2 nanoparticles are stable up to 51 GPa under quasihydrostatic conditions.

Non-hydrostatic conditions induce phase transition at lower pressures.

Grain size significantly affects the high pressure behavior of CeO2 nanomaterials.

Abstract

In situ high pressure XRD diffraction and Raman spectroscopy have been performed on 12 nm CeO2 nanoparticles. Surprisingly, under quasihydrostatic condition, 12 nm CeO2 nanoparticles maintain the fluorite-type structure in the whole pressure range (0-51 GPa) during the experiments, much more stable than the bulk counterpart (PT=31 GPa). In contrast, they experienced phase transition at pressure as low as 26 GPa under non-hydrostatic condition (adopting CsCl as pressure medium). Additionally, 32-36 nm CeO2 nanoparticles exhibit an onset pressure of phase transition at 35GPa under quasihydrostatic condition, and this onset pressure is much lower than our result. Further analysis shows both the experimental condition (i.e., quasihydrostatic or non-hydrostatic) and grain size effect have a significant impact on the high pressure behaviors of CeO2 nanomaterials.