Out-of-oven rapid synthesis of entropy stabilized oxides using radio frequency heating

Entropy stabilized oxides (ESOs) are a new class of stable hybrids and single phase metal oxides made from multiple ions with material properties somewhere between the con-stituent oxides, or occasionally entirely new properties. One of the limitations of ESOs is their energy-intensive fabrication process, which has resulted in slow development and scale-up of new ESOs. In this work, we present a novel energy-efficient ESO synthesis method that uses the ability of carbonaceous materials to heat rapidly in response to radio frequency (RF) fields in 1-200 MHz range. Using carbon fibers and graphene as RF sus-ceptors, synthesis of (Mg0.2Co0.2Ni0.2Cu0.2Zn0.2)O is achieved through RF-initiated com-bustion synthesis with heating rates of 203 degrees C/s at 20 W of input power. This method reduces the formation time of ESOs to less than a minute, allowing for much more efficient fabrication. The corresponding morphology and composition of the as-synthesized ESO-carbon fiber and ESO-graphene were studied using extensive spectroscopy and charac-terization. Additionally, single carbon fibers coated with ESO were tested for tensile strength and modulus; little change in mechanical properties was observed as compared to pristine fibers. This work opens an exciting frontier for the rapid synthesis of ESO-carbon composites using RF heating as a non-contact, rapid, and efficient manufacturing process. (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Automated summary

Entropy stabilized oxides (ESOs) are a new class of stable hybrids and single phase metal oxides with material properties in between the constituent oxides. However, their energy-intensive fabrication process has limited their development and scale-up. In this work, a novel energy-efficient ESO synthesis method using carbonaceous materials and radio frequency (RF) fields is proposed, enabling the synthesis of ESOs in less than a minute. The synthesized ESO-carbon composites show promising properties, and this method provides a rapid and efficient manufacturing process.