Ice crystals that flex and bend

Ice—cold, rigid, brittle . . . bendy? Researchers are surprised to find that ice is flexible and elastic at a microscopic scale when grown as tiny, fiber-like crystals (Science 2021, DOI: 10.1126/science.abh3754). Unlike naturally occurring ice, with air bubbles and cracks, the crystals in this study were nearly perfect and able to transmit light with less than 1% loss of intensity. Creating the crystals was tricky. The team, based at Zhejiang University and led by Xin Guo and Limin Tong, used an electric field in a freezing chamber to grow hexagonal crystals ranging from 10 μm down to less than 800 nm in diameter (shown). Most materials can bend when made very thin, like notoriously fragile glass fiber-optic cables. But these microfiber ice crystals can be bent into a minuscule radius of curvature, such that strains and stresses in the surface become incredibly high—almost the theoretical limit. “I found that really surprising,” says Erland M. Schulson, who studies ice at Dartmouth College and was not involved in the research. Scientists could use these microscopic ice crystals to study air pollution by looking at chemicals that stick to their surfaces, the researchers suggest. Even if applications don’t materialize soon, Schulson says, the ability to grow perfect ice crystals is “scientifically interesting.”