Ceramics are brittle and tend to crack under stress. But, researchers from Massachusetts Institute of Technology, Cambridge, along with colleagues in Singapore, say that they have found a way around that problem, at least for tiny objects.

When subjected to a load, the molecular structure of the ceramic material deforms instead of cracking. When heated, it returns to original shape. (Credit: Alan Lai)

They have made minuscule ceramic objects that are not only flexible, but also have “shape memory.” When bent and then heated, they return to their original shapes. Shape-memory materials, usually polymers or metals, but not ceramics, can bend and return to original configurations in response to temperature change. The key, they found, to shape-memory ceramics, was thinking small.

First, they created tiny ceramic objects made of zirconia, which were invisible to the naked eye. Then, they made the individual crystal grains span the entire small-scale structure, removing the crystal-grain boundaries where cracks are most likely to occur, which resulted in tiny samples of ceramic material with deformability equivalent to about 7 percent of their size. The tiny filaments, with a diameter of just 1 micrometer can be bent by 7 to 8 percent repeatedly without cracking, they say.

These materials could be used to develop micro- and nanodevices for biomedical applications, such as actuators on a chip, and self-deploying medical devices.