Architecting dual heterogeneous structures to achieve robust mechanical properties in ZrO2-SiO2 nanocrystalline ceramics

Heterostructured materials hold great potential for achieving superior mechanical properties. However, the majority of current studies on heterostructured ceramics have predominantly focused on layered systems. Here, we report a new 3YSZ-(ZrO 2 -SiO 2 ) dual-heterostructured ceramic composites (DHCCs) comprising 3 mol% yttria-stabilized zirconia (3YSZ) domains and ZrO 2 -SiO 2 domains. The DHCCs exhibited a dual-level hierarchical structure. Specifically, the 3YSZ domain consisted of submicron ZrO 2 grains, while the ZrO 2 -SiO 2 domain was composed of ZrO 2 nanograins dispersed within an amorphous SiO 2 matrix. To fabricate the DHCCs, hybrid powders were first synthesized by a chemical co-precipitation method, followed by sintering to produce dense DHCCs. The phase composition, microstructure, and mechanical properties of the DHCCs were characterized. Compared with the homogeneously structured ZrO 2 -SiO 2 ceramic, the DHCCs exhibited an 85.6% increase in strength and a 47.2% improvement in fracture toughness. Finally, the underlying strengthening and toughening mechanisms of the DHCCs were elucidated. These findings demonstrate that architecting dual-heterogeneous structures represents an effective strategy for achieving robust mechanical properties.