Disorder in M<sub>n+1</sub>AX<sub>n</sub> phases at the atomic scale.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 30733461.
- Also identified by DOI 10.1038/s41467-019-08588-1 and PMC identifier 6367347.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Atomic disordering in materials alters their physical and chemical properties and can subsequently affect their performance. In complex ceramic materials, it is a challenge to understand the nature of structural disordering, due to the difficulty of direct, atomic-scale experimental observations. Here we report the direct imaging of ion irradiation-induced antisite defects in M<sub>n+1</sub>AX<sub>n</sub> phases using double C<sub>S</sub>-corrected scanning transmission electron microscopy and provide compelling evidence of order-to-disorder phase transformations, overturning the conventional view that irradiation causes phase decomposition to binary fcc-structured M<sub>n+1</sub>X<sub>n</sub>. With the formation of uniformly distributed cation antisite defects and the rearrangement of X anions, disordered solid solution γ-(M<sub>n+1</sub>A)X<sub>n</sub> phases are formed at low ion fluences, followed by gradual transitions to solid solution fcc-structured (M<sub>n+1</sub>A)X<sub>n</sub> phases. This study provides a comprehensive understanding of the order-to-disorder transformations in M<sub>n+1</sub>AX<sub>n</sub> phases and proposes a method for the synthesis of new solid solution (M<sub>n+1</sub>A)X<sub>n</sub> phases by tailoring the disorder.