Crystalline-amorphous dual-phase ceramic nanocomposites regulated by entropy engineering

Solid-state reaction (SSR) is frequently used to fabricate bulk high-entropy ceramics (HECs). However, a high temperature and a long dwelling time are typically required to allow the occurrence of SSR. Meanwhile, conventional HECs were typically composed of single-phase solid solution with micrograins. It is of great interest to develop nanocrystalline dual-phase HECs under mild conditions. Here, we fabricated entropy-mediated crystalline-amorphous dual-phase ceramic nanocomposites, and the fabrication process showed significantly higher energy and time efficiency than the conventional SSR. The nanocomposites were composed of entropy-mediated nanoparticles (EM-NPs) embedded in an amorphous SiO2 matrix. The constituent elements were homogeneously distributed in the EM-NPs at the atomic level. The EM-NPs were dislocations-free but with lattice strain, and they showed a strong coarsening tendency during annealing. The nanocomposites showed a significant solid solution hardening effect. The reported results would provide useful guidance to fabricate nanocrystalline HECs with crystalline-amorphous dual-phase microstructure. Formation mechanism of traditional single-phase HECs and the new crystalline-amorphous dual-phase HEC. image