Nacre toughening due to cooperative plastic deformation of co-oriented aragonite columns

Nacre’s structure-property relationships have been a source of inspiration for designing advanced functional materials with both high strength and toughness. These outstanding mechanical properties have been mostly attributed to the interplay between aragonite platelets and organic matrix in the typical brick-and-mortar structure. Here, we show that crystallographically co-oriented stacks of aragonite platelets—aragonite columns—define another hierarchical level that contributes to the toughening of nacre. By correlating piezo-Raman and micro-indentation results, we quantify the residual strain energy associated with strain hardening capacity. Our findings suggest that aragonite columns with characteristic dimensions of around 20 µm in height effectively store energy through cooperative plastic deformation. The existence of a larger length scale beyond the brick-and-mortar structure offers an opportunity for a more efficient implementation of biomimetic strategies.