Ceramics International: Influence of the atmosphere on the formation of high-entropy oxides within the Co–Cu–Fe–Mg–Mn–Ni–O system via reactive flash sintering

 

Ceramics International

Volume 50, Issue 21, Part B, 1 November 2024, Pages 42276-42285

 

Influence of the atmosphere on the formation of high-entropy oxides within the Co–Cu–Fe–Mg–Mn–Ni–O system via reactive flash sintering

 A.F. Manchón-Gordón a, C. Lobo-Llamas a, S. Molina-Molina a, A. Perejón a b
, P.E. Sánchez-Jiménez a, L.A. Pérez-Maqueda a

a
    Instituto de Ciencia de Materiales de Sevilla, ICMSE CSIC-Universidad de Sevilla, C. Américo Vespucio 49, Sevilla, 41092, Spain

b
    Departamento de Química Inorgánica, Facultad de Química, Universidad de Sevilla, Sevilla, 41012, Spain

Received 8 May 2024, Revised 22 July 2024, Accepted 4 August 2024, Available online 5 August 2024, Version of Record 27 September 2024.

 

Abstract

In this study, the feasibility of preparing quinary equimolar high-entropy oxides within the Co–Cu–Fe–Mg–Mn–Ni–O system was explored using the reactive flash sintering (RFS) technique. Various compositions were tested using this technique under atmosphere pressure, leading to the formation of two primary phases: rock-salt and spinel. Conversely, a new high-entropy oxide was produced as a single-phase material with the composition (Co_0.2,Cu_0.2,Mg_0.2,Mn_0.2,Ni_0.2)O when RFS experiments were conducted in nitrogen atmosphere. The reducing conditions achieved in nitrogen enabled the incorporation of cations with oxidation states different from +2 into the rock-salt lattice, emphasizing the critical role of the processing atmosphere, whether inert or oxidizing, in the formation of high-entropy oxides. The electrical characterization of this material was obtained via impedance spectroscopy, exhibiting a homogeneous response attributed to electronic conduction with a temperature dependence characteristic of disordered systems.

 

https://www.sciencedirect.com/science/article/pii/S0272884224035028