Abstract Scope |
Various single-phase equimolar five-component high-entropy ceramics (HECs), e.g., MB2 [Scientific Reports 2016], MB [Scripta 2020], M3B4 [JAC 2021], MB4 [JECS 2020] and MB6 [JECS 2021] borides, MSi2 [JMat 2019] and M3Si5 [Scripta 2022] silicides, aluminides [Science Bulletin 2019], perovskite [Scripta 2018], fluorite [JECS 2018] and pyrochlore [Scripta 2020] oxides have been fabricated. We further proposed to extend HECs to "compositionally complex ceramics (CCCs)" [JECS 2020 and JMS 2020] in include non-equimolar compositions and short- and long-range ordering (that reduce configurational entropies but offer additional dimensions to tailor and improve various properties), as well as reported the first dual-phase HECs/CCCs [JECS 2020]. Using fluorite-based oxides as model systems, our recent discoveries of long- and short- range ordering, composition- and redox-induced order-disorder transitions, and ultrahigh-entropy phases in 10- to 21-component systems [Acta 2021 & 2022, Scripta 2022, JAC 2022, and many unpublished results] will be discussed as the focus of this talk. |