ontaneous symmetry breaking discovers the formation of aeroplane-like ZnO nanocrystals

Yan Zhou,1,2 Junyan Zhang,1,a) Bin Zhang,1 Li Qiang,1 Yuqing Da,3,b) Gang Su,4,c) and Jiangong Li2,d) 1 Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China 2 Institute of Materials Science and Engineering, Lanzhou University, Lanzhou 730000, China 3 Tianhua Institute of Chemical Machinery and Automation, Lanzhou 730060, China 4 College of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China (Received 28 January 2014; accepted 27 February 2014; published online 24 March 2014)

Although symmetry breaking is widely realized as one of the most powerful tools in modern scientific researches, it is unclear how symmetry breaking plays its role in nanocosm. Here, we show a correlation between spontaneous symmetry breaking and the formation of nanocrystals. In our experiments, some ZnO nanocrystals, including ZnO tetrapods, rod-based tetrapods, and aeroplane-like crystals, presented with specific structures and symmetries leading to an unexpected process of spontaneous symmetry breaking. According to the rule of spontaneous symmetry breaking, a hypothesis was proposed that the aeroplane-like nanocrystals might be resulted from the unequal development of the crystal twinnings. Subsequent work supported this hypothesis and proved the dramatic effect of spontaneous symmetry breaking. This work applies the rule of spontaneous symmetry breaking to the formation mechanisms for nanocrystals and highlights the causal contribution of spontaneous symmetry breaking to the intricate behaviors of the particles at nanoscale