Regensburg 2019 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 2: Topical session (Symposium MM): High entropy and compositionally complex alloys

MM 2.7: Vortrag

Montag, 1. April 2019, 12:30–12:45, H43

Tunable optical properties of (Mg-Co-Cu-Ni-Zn)O High Entropy Oxide thin films — •Emeline Michel — I. Physikalisches Institut (IA), RWTH Aachen University, D-52056 Aachen, Germany

Multi-component High Entropy Alloys have been shown to be interesting for their favorable mechanical properties, e.g. high fracture toughness, and resistance to oxidizing or corrosive environment. The enhanced properties of High Entropy Alloys are due to the entropy-driven formation of simple phases. However, the oxidation of these materials, leading to High Entropy Oxides, is poorly understood. High Entropy Oxides have been recently studied by Rost et al., who verified the entropy stabilization ansatz and showed that configurational disorder provides an alternative route to new materials discovery.

Here we investigate the oxidation behaviour of High Entropy Alloys from the Mg-Co-Cu-Ni-Zn metallic system. Therefore, thin films of High Entropy Oxides are deposited by reactive sputtering. Surprisingly, we observe that the system exhibits a pronounced, broad sub-bandgap absorption. Moreover, the oxygen partial pressure used to deposit the (Mg-Co-Cu-Ni-Zn)O thin films is a tuning parameter of the optical properties of the system. The correlation between the tunable optical properties of (Mg-Co-Cu-Ni-Zn)O thin films and its structural changes is investigated.