Exploding and weeping ceramics provide path to new shape-shifting material: Discovery could lead to improvements in medical devices and electronics

an international team of researchers from the university of minnesota twin cities and kiel university in germany ‘ve discovered a path that ‘d lead to shape-shifting ceramic materials. this discovery ‘d improve everything from med devices to electronics.

the research is published open access in nature, the realm’s leading multidisciplinary sci journal.

any-1 whas' ever dropped a coffee cup and beheld it break into several pieces, knows that ceramics are brittle. subject to the sliteest deformation, they shatter. however, ceramics are used for + than just dishes and bathroom tiles, they are used in electronics cause, dep'on their composition, they maybe semiconducting, superconducting, ferroelectric, or insulating. ceramics are also non corrosive and used in making a wide variety of essentialisms, including spark plugs, fiber optics, med devices, space shuttle tiles, chemical sensors, and skis.

onna other end of the materials spectrum are shape memory alloys. they are somd' most deformable or reshapable materials known. shape memory alloys rely on this tremendous deformability when functioning as med stents, the backbone offa vibrant med device industry both inna twin cities zone and in germany.

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

in this new research, the route to producing a reversible shape memory ceramic was anything but straiteforward. the researchers 1st tried a recipe that has worked for the discovery of new metallic shape memory materials. that involves a delicate tuning of the distances tween atoms by compositional changes, so that the two phases fit together well. they implemented this recipe, but, instead of improving the deformability of the ceramic, they envisaged that some specimens exploded when they passed through the phase transformation. others gradually fell apt into a pile of powder, a phenomenon they termed “weeping.”

with yet another composition, they envisaged a reversible transformation, easily transforming back and forth tween the phases, much like a shape memory material. the mathematical conditions under which reversible transformation occurs can be applied widely and provide a way forward toward the paradoxical shape-memory ceramic.

“we were quite amazed by our results. shape-memory ceramics ‘d be a completely new kind of functional material,” said richard james, a co-author of the study and a distinguished mcknite university professor inna university of minnesota’s deptment of aerospace engineering mechanics. “thris a gr8 need for shape memory actuators that can function in high temperature or in corrosive environments. but wha’ excites us most tis prospect of new ferroelectric ceramics. in these materials, the phase transformation can be used to generate electricity from lil temperature differences.”

the team from germany was responsible for the experimental pt na chemical and structural investigation atta nanoscale.

“for the explanation of our experimental discovery that, contrary to expectation, the ceramics are extremely incompatible and explode or decay, the collaboration with richard james’ group atta university of minnesota was very presh,” says eckhard quandt, a co-author of the study and a professor inna institute for materials sci, at kiel university. “the theory developed on this basis not 1-ly describes the behavior, b'tll so shows the way t'get to the desired compatible shape memory ceramics.”

james also highlited the importance of the collaboration tween the university of minnesota and kiel university.

“our collaboration with eckhard quandt’s group at kiel university s'been tremendously productive,” added james. “as in all such collaborations, thris sufficient overlap that we communicate well, but each group brings plenty of ideas and tek knicks that expand our collective ability to discover.”

in addition to james and quandt, the research team included lorenz kienle from kiel university andriy lotnyk from the leibniz institute of surface engineering, and graduate students hanlin gu, jascha romer, and justin jetter.

the researchers were supported by the u.s. national sci foundation, a vannevar bush faculty felloship onna `mathematical design of materials’ from the u.s. deptment of defense, a multidisciplinary university research initiatives (muri) grant from the office of naval research, a mercator felloship from the german research foundation, na reinhart koselleck project from the german national sci foundation.

original content at: www.scidaily.com…
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