Growth of ZrTe₅ nanostructures. (a) A schematic drawing of the growth setup for the iodine vapor transport method. A two-bulb ampoule is used. Zirconium shots and iodine particles are placed in one bulb, which is held at a higher temperature, 540 °C. Tellurium powder and silicon substrates are placed in the other bulb, which is held at a lower temperature, 480 °C and 450 °C, respectively. (b)–(e) A series of SEM images of grown nanostructures with increasing magnifications. ZrTe₅ nanoribbons are grown on a mattress of ZrTe₃ and Te crystals. A recession of the silicon substrate due to iodine etching can be observed in (d) and (e). (f) Energy-dispersive x-ray spectroscopy of nanoribbon, indicating ZrTe₅. (g) A spectrum taken at the root of the nanoribbon, indicating ZrTe₃. The black squares in (e) mark the spots where the spectra were taken.