It might look like Manhattan or Chicago, but this cityscape is actually formed from the world鈥檚 first synthetic 鈥渘anocolumns鈥�. Towering between two and five micrometres above a sapphire base, each 鈥渟kyscraper鈥� is a column of stacked zinc oxide crystals. Single hexagonal crystals form each 鈥渟torey鈥�, gradually diminishing in diameter with height.
Yunqi Liu and his team at the Chinese Academy of Sciences鈥� Institute of Chemistry in Beijing made the towers in a furnace by reacting zinc sulphide with oxygen at 950 掳C. Zinc oxide is a semiconductor that serves a variety of functions in conductive films and electronic transducers. The researchers speculate that the towers could serve as nano-components in optoelectronic devices such as flat-panel displays (Chemical Communications, 2003, p 1304).