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Strong, lightweight, and recoverable three-dimensional ceramic nanolattices

Science  12 Sep 2014:
Vol. 345, Issue 6202, pp. 1322-1326
DOI: 10.1126/science.1255908

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Compressive, ductile ceramic nanolattices

Ceramics are strong and stiff, but their limited ability to stretch like putty or steels makes them unsuitable for many engineering applications. Meza et al. constructed ceramic nanolattices from aluminum oxide, in which the beams are designed to stretch rather than bend. A key parameter in lattice design is the ratio of the wall thickness to the beam radius. When that ratio is small enough, compressing the beams does not break them. That way, the nanolattices can be highly compressed and recover to something close to their original shape when the stress is removed.

Science, this issue p. 1322

Abstract

Ceramics have some of the highest strength- and stiffness-to-weight ratios of any material but are suboptimal for use as structural materials because of their brittleness and sensitivity to flaws. We demonstrate the creation of structural metamaterials composed of nanoscale ceramics that are simultaneously ultralight, strong, and energy-absorbing and can recover their original shape after compressions in excess of 50% strain. Hollow-tube alumina nanolattices were fabricated using two-photon lithography, atomic layer deposition, and oxygen plasma etching. Structures were made with wall thicknesses of 5 to 60 nanometers and densities of 6.3 to 258 kilograms per cubic meter. Compression experiments revealed that optimizing the wall thickness-to-radius ratio of the tubes can suppress brittle fracture in the constituent solid in favor of elastic shell buckling, resulting in ductile-like deformation and recoverability.

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