Don’t mess with ice. When it’s stressed, ice can get seriously sparky.
Scientists have discovered that ordinary ice—the same substance found in iced coffee or the frosty sprinkle on mountaintops—is imbued with remarkable electromechanical properties. Ice is flexoelectric, so when it’s bent, stretched, or twisted, it can generate electricity, according to a Nature Physics paper published August 27. What’s more, ice’s peculiar electric properties appear to change with temperature, leading researchers to wonder what else it’s hiding.
The paper changes “how we view ice: from a passive material to an active material that may be at play for both fundamentals and applications,”
Xin Wen, study lead author and a nanophysicist at Institut Catala de Nanociencia i Nanotecnologia in Spain, told Gizmodo in an email.
A cold case in molecular chemistry
An unsolved mystery in molecular chemistry is why the structure of ice prevents it from being piezoelectric. By piezoelectricity, scientists refer to the generation of an electric charge when mechanical stress changes a solid’s overall polarity, or electric dipole moment.
The water molecules that make up an ice crystal are polarized. But when these individual molecules organize into a hexagonal crystal, the geometric arrangement randomly orients the dipoles of these water molecules. As a result, the final system can’t generate any piezoelectricity.
However, it’s well known that ice can naturally generate electricity, an example being how lightning strikes emerge from the collisions between charged ice particles. Because ice doesn’t appear to be piezoelectric, scientists were confused as to how the ice particles became charged in the first place.
“Despite the ongoing interest and large body of knowledge on ice, new phases and anomalous properties continue to be discovered,” the researchers noted in the paper, adding that this unsatisfactory knowledge gap suggests “our understanding of this ubiquitous material is incomplete.”
A shockingly simple solution
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