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EXAFS reveals structural disorder and magnetic properties of high entropy alloys

2 November 2022 | News
by Ian Michael
Structure of the Cantor alloy

High entropy alloys (HEAs) consist of five or more different metallic elements and are an extremely interesting class of materials with a great diversity of potential applications. Since their macroscopic properties are strongly dependent on interatomic interactions, it is interesting to probe the local structure and structural disorder around each individual element by element-specific techniques. Now, a team has examined a so-called Cantor alloy—a model system to study the high-entropy effects on the local and macroscopic scales.

To investigate the local environment of individual components, the team used multi-edge X-ray absorption spectroscopy (EXAFS) at BESSY II and then the reverse Monte Carlo method to analyse the collected data. The magnetic properties of each element of the alloy were additionally probed using X-ray magnetic circular dichroism (XMCD). By conventional magnetometry, the scientists proved the presence of magnetic phase transitions and found some signatures of a complex magnetic ordering with a coexistence of different magnetic phases.

The results from the examined nanocrystalline film made of this alloy demonstrate some common trends as compared to a bulk sample, e.g. the largest lattice relaxations of chromium and still intriguing magnetic behaviour of manganese, which are consistent with the macroscopic magnetic behaviour of the film.

“High-entropy alloys are an extremely diverse and exciting class of materials”, says Dr Alevtina Smekhova, physicist at HZB. “By probing the behaviour of individual components at the atomic scale, we would gain valuable clues for the further development of new complex systems with the desired multifunctionality”, she says.

 

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Read the original journal paper in Nano Research

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