Strong, tough and stiff bioinspired ceramics from brittle constituents

High strength and high toughness are usually mutually exclusive in engineering materials. In ceramics, improving toughness usually relies on the introduction of a metallic or polymeric ductile phase, but this decreases the material’s strength and stiffness as well as its high-temperature stability. Although natural materials that are both strong and tough rely on a combination of mechanisms operating at different length scales, the relevant structures have been extremely difficult to replicate. Here, we report a bioinspired approach based on widespread ceramic processing techniques for the fabrication of bulk ceramics without a ductile phase and with a unique combination of high strength (470 MPa), high toughness (17.3 MPa m1/2), and high stiffness (290 GPa). Because only mineral constituents are needed, these ceramics retain their mechanical properties at high temperatures (600 °C). Our bioinspired, material-independent approach should find uses in the design and processing of materials for structural, transportation and energy-related applications. The toughness of ceramic materials can be improved by introducing a polymeric or metallic ductile phase, yet most often this is at the expense of strength, stiffness and high-temperature stability. Now, a simple processing route based on widespread ceramic processing techniques is shown to produce bulk ceramics that mimic the structure of natural nacre and have a unique combination of high strength, toughness and stiffness, even at high temperatures.