Shape-shifting ceramics: Medical Manufacturing

An international team of researchers from University of Minnesota, Twin Cities, and Kiel University in Germany has discovered a path that could lead to shape-shifting ceramic materials. This discovery could improve everything from medical devices to electronics.

Anyone who ever has dropped a coffee cup and watched it break into several pieces knows that ceramics are brittle. Subject to the slightest deformation, they shatter. However, they are used for more than dishes and bathroom tiles. Ceramics are used in electronics because, depending on their composition, they may be semiconducting, superconducting, ferroelectric or insulating. Ceramics are also noncorrosive and used to make a wide variety of products, including spark plugs, fiber optics, medical devices, space shuttle tiles, chemical sensors and skis.

Shape memory alloys are on the other end of the materials spectrum. They are some of the most deformable or reshapable materials known. Shape memory alloys rely on this tremendous deformability when functioning as medical stents, which are the backbone of vibrant medical device industries in the Twin Cities and Germany.

Creating shape-shifting materials is not an easy process. It involves a delicate tuning of the distances between atoms by compositional changes so the two phases fit together well. This diagram shows what happened when researchers implemented this recipe with one sample of ceramic material. Instead of improving deformability of the ceramic, they observed that some specimens gradually fell apart into a pile of powder, a phenomenon they termed “weeping.” Image courtesy of Hanlin Gu et al., University of Minnesota and Kiel University

The origin of this shape-shifting behavior is a solid-to-solid phase transformation. Different from the process of crystallization-melting-recrystallization, crystalline solid-solid transitions take place solely in the solid state. By changing temperature or pressure, a crystalline solid can be transformed into another crystalline solid without entering a liquid phase.