Elastic ice microfibers

One well known characteristic of ice is that it fractures instead of bending when strained. This characteristic is caused by the inevitable defects introduced into the ice structure during solidification. Xu et al. show that very thin, carefully grown ice microfibers can bend a lot, up to about 11%, and still remain elastic (see the Perspective by Schulson). This value is reasonably close to theoretical limits previously estimated. The fibers are also super clear, allowing for efficient light transmission. Science , abh3754, this issue p. 187 ; see also abj4441, p. 158 Ice is usually very brittle but becomes remarkably elastic when grown as long and thin fibers. Ice is known to be a rigid and brittle crystal that fractures when deformed. We demonstrate that ice grown as single-crystal ice microfibers (IMFs) with diameters ranging from 10 micrometers to less than 800 nanometers is highly elastic. Under cryotemperature, we could reversibly bend the IMFs up to a maximum strain of 10.9%, which approaches the theoretical elastic limit. We also observed a pressure-induced phase transition of ice from Ih to II on the compressive side of sharply bent IMFs. The high optical quality allows for low-loss optical waveguiding and whispering-gallery-mode resonance in our IMFs. The discovery of these flexible ice fibers opens opportunities for exploring ice physics and ice-related technology on micro- and nanometer scales.