AsianScientist (Sep. 7, 2016) – Researchers at Japan’s Hokkaido University have developed a ferroelectric crystal that turns into a plastic, more pliable phase at higher temperatures. Their work was published in Nature Chemistry.
Applying an electric field to some materials causes their atoms to ‘switch’ their electric polarization from one direction to another, making one side of the material positive and the other negative. This switching property of ferroelectric materials allows them to be used in a wide range of applications. For example, ferroelectric capacitors are used to store binary bits of data in memory devices.
The crystal developed by first author Dr. Jun Harada and colleagues is ferroelectric above room temperature, then turns into a plastic, more pliable phase at higher temperatures. At the higher temperatures, the molecules in the crystal have randomly different polarity axes, but they can be aligned in one direction by applying an electric field as the crystal cools, bringing it back to a ferroelectric state.
Being able to control the polarity in this manner addresses a major challenge previously faced by researchers working with organic compound-based ferroelectric crystals, which are less symmetric than inorganic crystals.
This plasticity—as opposed to fracturing that occurs in regular organic and inorganic crystals when mechanical stress is applied—makes it extremely advantageous for use as a thin ferroelectric film in devices. An example would be non-volatile ferroelectric random-access memory devices, which maintain memory when the power is turned off.
The article can be found at: Harada et al. (2016) Directionally Tunable and Mechanically Deformable Ferroelectric Crystals from Rotating Polar Globular Ionic Molecules.
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Source: Hokkaido University.
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