Transmission electron microscopy observation of nanoscale deformation structures in nacre

The mechanical performance of nacre in seashells is generally described in terms of mesoscale mechanisms between mineral plates within the organic polymer matrix. However, recent work has reported nanostructures and organic material within individual plates and associated deformation mechanisms. In this work, we further investigated the nanoscale structure and mechanical behavior within individual plates of nacre by using two methods to induce fracture of plates: microindentation with focused ion beam preparation and ultramicrotomy. Using transmission electron microscopy, we observed deformation nanostructures and organic matrix within plates and identified nanoscale mechanisms, such as separation, shear, and matrix crack bridging.