With its unique combination of durability and translucence, the shells of a sea creature mollusk Placuna placenta, commonly known as windowpane oyster, have been used for years as a natural substitute for glass.
The researchers at the Massachusetts Institute of Technology (MIT) studied the structure of the shells to find out why they were strong, despite being made almost entirely from brittle calcite.
The findings of the study will be published in a forthcoming issue of Nature Materials.
During the study, the researchers found that the mollusks evolved a nanostructure that allows light to pass through nearly without obstruction. Moreover, the material also isolates any penetration damage at the atomic level, leading to prevention of cracking.
Graduate student Ling Li and professor Christine Ortiz used a diamond-tipped utensil to indent the surface of mollusk shells. Further, the researcher used diffraction and a transmission electron microscope to keenly observe the development. They found that the particles on the leading edge of the damage broke into two identical blocks. The researchers named the phenomenon as “twinning”.
Presently, ceramic armor has limitations: it can stop one bullet, but only at the cost of widespread structural damage. The twinning principle could inspire ways to re-enforce the materials. Plus, given that these mollusk shells can be clear enough to see through, Ortiz says synthetic designs could mimic them to create face masks or armored windows.
The MIT researchers say, the findings of the study could positively influence the design of armor in military and manufacturing. The twinning technique could help in strengthening these materials. Today’s ceramic armor has several limitations. They have the ability to stop one bullet and that too at the cost of widespread structural damage.
