It is not easy to create shape-shifting materials. The two phases fit together well because of the delicate tuning of the distances between atoms. The diagram shows what happened when researchers implemented this recipe. They observed that some of the ceramic fell apart into a pile of powder, instead of improving its deformability. Credit: Gu, et al., University of Minnesota.
A group of researchers from the University of Minnesota Twin Cities and the University of Kiel in Germany have found a path that could lead to shape-shifting ceramic materials. This discovery could improve a lot of things.
The research is published in a journal.
Ceramics are brittle, and anyone who has ever dropped a coffee cup and watched it break into pieces knows that. They shatter if they are subjected to the smallest of changes. Ceramics are used for more than just dishes and bathroom tiles, they are also used in electronics because of their composition. Ceramics are non corrosive and can be used to make a wide variety of products, including spark plugs, fiber optics, medical devices, space shuttle tiles, chemical sensors, and skis.
Shapes memory alloys are on the other side of the spectrum. They are some of the most reshapable materials. The Twin Cities area and Germany have a vibrant medical device industry that relies on this tremendous deformability.
A solid-to-solid phase transformation is the origin of this behavior. Crystallization–melting–recrystallization is different from the process of solid–solid transitions. A solid can be transformed into another solid without entering a liquid phase.
A sample of ceramic material has good compatibility between phases, but not good compatibility at the grain boundaries. It explodes when it passes through a transformation. Jascha Rohmer is a student at the University.
The route to producing a memory ceramic was not easy. The researchers tried a recipe that worked for them. The two phases fit together well if the distances between atoms are adjusted by the composition of the atoms. They implemented this recipe, but instead of improving the ceramic's deformability, they observed that some specimen exploded when they passed through the phase transformation. They termed it "weeping", as others gradually fell into a pile of powder.
They observed a transformation that was similar to a shape memory material. The mathematical conditions under which the transformation occurs can be applied widely and provide a way forward.
We were amazed by our results. Richard James is a co-author of the study and a professor in the University of Minnesota's Department of Aeronautical Engineering Mechanics. There is a need for shape memory actuators that can function in high temperature or corrosive environments. New ferroelectric ceramics are exciting to us. The phase transformation can be used to generate electricity.
The sample in this video has good compatibility between phases, but poor compatibility at grain boundaries. It begins to fall apart at the grain boundaries. The authors call itweeping. Jascha Rohmer is a student at the University.
The team from Germany was responsible for the experimental part.
The collaboration with Richard James' group at the University of Minnesota was very valuable for the explanation of the experimental discovery that the ceramics are incompatible and explode or decay. The way to get to the desired compatible shape memory ceramics is shown in the theory developed on this basis.
James highlighted the importance of the collaboration between the University of Minnesota and Kiel University.
A sample of ceramic material is similar to a shape memory material. The mathematical conditions under which the transformation occurs can be applied widely and provide a way forward. Jascha Rohmer is a student at the University.
James said that their collaboration with the group at Kiel University has been productive. There is enough overlap that we communicate well, but each group brings plenty of ideas and techniques that expand our collective ability to discover.
The research team included James and Quandt, as well as graduate students Hanlin Gu, Jascha Romer, and Justin Jetter.
Hanlin Gu and her colleagues wrote about weeping ceramics in Nature. There is a DOI of 10.1038/s41586-021-03975-5.
Nature journal information.
The path to new shape-shifting material is provided by exploding and weeping ceramics.
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