High entropy oxides

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As Hochentropie oxide (HEO) refers to complex oxides , the five or more different metal cations contained in the same amount, and a single-phase crystal structure have. Depending on the composition, a distinction is made between transition metal HEO (TM-HEO), rare earth HEO (RE-HEO) and mixed HEO (TM-RE-HEO). The first publication on HEOs was by the group of Christina M. Rost et al. at North Carolina State University in 2015.

properties

In the case of high entropy oxides, the various metal cations form a common crystal lattice, even if the typical crystal structures of the individual elements differ significantly from one another and the cations are distributed to the positions in the crystal without any recognizable order. The compounds often have interesting and unexpected properties, such as exceptionally high room temperature lithium-ion conductivities for solid state electrolytes in TM-HEO, very narrow and tailored band gaps in RE-HEO and colossal dielectric constants in TM-HEO. The special properties of HEO are based on entropy stabilization , making them comparable to the more well-known high entropy alloys .

One of the first investigated HEOs with a saline structure was the compound (Co 0.2 Cu 0.2 Mg 0.2 Ni 0.2 Zn 0.2 ) O. Compounds with a fluorite , perovskite and spinel structure were also investigated later .

use

High entropy oxides are the subject of research for rechargeable batteries in order to significantly improve their storage capacity and cycle stability.

Individual evidence

  1. ↑ a b c d KIT press release 113/2018: Disorder can stabilize batteries , accessed on June 29, 2019.
  2. ↑ a b c Sarkar, A., Wang, Q., Schiele, A., Chellali, MR, Bhattacharya, SS, Wang, D., Brezesinski, T., Hahn, H., Velasco, L., Spreading, B. ., in High ‐ Entropy Oxides: Fundamental Aspects and Electrochemical Properties , Adv. Mater. 2019, 31, 1806236. doi : 10.1002 / adma.201806236
  3. ↑ High Entropy Materials: INT- Research - High Entropy Materials , accessed June 29, 2019.
  4. ↑ Christina M. Rost, Edward Sachet a. a .: Entropy-stabilized oxides. In: Nature Communications. 6, 2015, doi : 10.1038 / ncomms9485 .
  5. ↑ Ralf Witte, Abhishek Sarkar u. a .: High-entropy oxides: An emerging prospect for magnetic rare-earth transition metal perovskites. In: Physical Review Materials. 3, 2019, doi : 10.1103 / PhysRevMaterials.3.034406 .
  6. ↑ Qingsong Wang, Abhishek Sarkar et al. a .: High entropy oxides as anode material for Li-ion battery applications: A practical approach. In: Electrochemistry Communications. 100, 2019, p. 121, doi : 10.1016 / j.elecom.2019.02.001 .