Shape-memory ceramic promises a whole new material

German and American engineers have developed a new method to create shape-changing ceramics that could be used in medical devices and electronics and even to generate power.

(Credit: Jascha Rohmer, University of Kiel)

The method was inspired by the solid-to-solid phase transformation exhibited by certain shape-memory alloys. To encourage similar behavior in ceramics, the researchers fine-tuned the distances between the atoms through compositional changes, with the aim of ensuring that the two phases fit together well.

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Although some experimental attempts ended with samples exploding or collapsing into powder, the team eventually achieved a reversible transformation, moving easily between phases, much like a shape-memory material.

According to the researchers, the conditions under which this reversible transformation occurred can be widely applied, paving the way for the creation of shape-memory ceramics. The work is described in the journal Nature.

“We were quite surprised with our results. Shape-memory ceramics would be an entirely new type of functional material,” said study co-author Richard James, a professor in the Department of Aerospace Engineering Mechanics at the University of Minnesota.

“There is a great need for shape memory actuators that can operate in high temperature or corrosive environments. But what excites us most is the prospect of new ferroelectric ceramics. In these materials, phase transformation can be used to generate electricity from small temperature differences.

The team from the German University of Kiel was responsible for the experimental part of the study as well as the chemical and structural study at the nanoscale.

“For the explanation of our experimental finding that, contrary to expectations, ceramics are extremely incompatible and either explode or decompose, the collaboration with Richard James’ group at the University of Minnesota has been invaluable,” said Eckhard Quandt. , co-author of the studies and professor at the Institute of Materials Science at the University of Kiel.

“The theory developed on this basis not only describes the behavior, but also shows the way to obtain the desired compatible shape memory ceramics.”

According to James, the collaboration between the two institutions has been central to the success of the project, with different ideas and approaches ultimately helping the team push the boundaries of what is possible with ceramic materials.

“Our collaboration with Eckhard Quandt’s group at the University of Kiel has been extremely productive,” he added. “As with all of these collaborations, there’s enough overlap that we communicate well, but each group brings a lot of ideas and techniques that expand our collective ability to discover.”

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