A signature of arts and crafts sessions, the Mbius strip--a seemingly endless ribbon with only one side and one edge that can be made from construction paper and sticky tape--has been given a new look. According to a report published today in the journal Nature, scientists have succeeded in growing crystals in the form of Mbius structures.
A piece of ribbon or paper can be twisted and turned easily, so a regular Mbius strip itself is no great feat of engineering. Crystals, in contrast, contain an inherently rigid structure. To manufacture their miniature Mbius strips, Satoshi Tanda of Hokkaido University in Japan and his colleagues placed a mixture of selenium (Se) and niobium (Nb) powder in a quartz tube and heated it to temperatures greater than 700 degrees Celsius. Under these conditions, Se changes among vapor, mist and liquid phases. The tiny drops of liquid selenium acted as spools on which the strips formed (see image). As the crystals of NbSe3 grew, they wrapped around the droplet and the two ends met, making a seamless ring the diameter of a human hair. By changing the growing conditions, the researchers coaxed the crystals into twisting either once, resulting in a Mbius strip, or twice, which created a "figure-of-eight" crystal strip.
Exactly what these mini Mbius strips could be used for is unclear. But the scientists suggest that strips of different sizes could be manufactured by varying the size of the liquid drops, and they have already applied their technique to a number of other compounds. The authors propose that these strangely shaped crystals could aid studies of the quantum mechanical effects of surface features.