# Unveiling Swift Heavy Ion Track Morphology in Sr-Based High-Entropy Perovskites

## TL;DR

This study explores how high-entropy oxides respond to heavy ion irradiation, revealing unique nanoscale damage patterns and enhanced stability.

## Contribution

The work provides new atomic-level insights into irradiation effects in high-entropy perovskites, showing distinct track morphology and stability.

## Key findings

- Discontinuous and partially recrystallized ion tracks form in Sr(HE)O3 under irradiation.
- The crystalline–amorphous interface in Sr(HE)O3 shows minimal lattice distortion.
- Amorphous regions in Sr(HE)O3 ion tracks remain stable under electron irradiation.

## Abstract

The incorporation of multiple cations on a single lattice
site
in the high-entropy oxides is considered the key driving factor for
modifying the known atomic-level response to energetic ion irradiation
due to the presence of structural disorder; however, these effects
are not well-understood yet. In this work, we present atomic-level
insight into irradiation-induced nanoscale phase transformations in
a perovskite-structured high-entropy oxide, Sr­(Zr0.2Sn0.2Ti0.2Hf0.2Nb0.2)­O3 (Sr­(HE)­O3), subjected to 774 MeV swift Xe heavy ions,
where damage is dominated by inelastic ion–lattice interactions.
While these ions generally are known to create nanoscale disordered
channels, “ion tracks”, along the penetration direction
in the material, this study shows the formation of discontinuous and
partially recrystallized ion tracks in Sr­(HE)­O3. Compared
to SrTiO3 irradiated under identical energy loss conditions,
the ion tracks in Sr­(HE)­O3 exhibit significantly reduced
diameters and a markedly different interfacial structure. Notably,
the crystalline–amorphous interface in Sr­(HE)­O3 shows
minimal lattice distortion, confined to approximately 2–3 monolayers,
in contrast to the extended disordered shell commonly observed in
SrTiO3. Using in situ atomic-resolution electron microscopy,
we further demonstrate that the amorphous/disordered regions within
Sr­(HE)­O3 ion tracks remain highly stable under electron
irradiation, whereas tracks in SrTiO3 readily recrystallize.
This enhanced stability is attributed to the dominance of structural
and chemical complexity arising from multiple B-site cations, which
suppress defect migration and templated recrystallization driven by
electronic excitations and local heating. Overall, this study highlights
how high-entropy oxide chemistry fundamentally reshapes irradiation
damage evolution, offering insights into defect formation and phase
stability under extreme conditions.