writer：Guoliang Zhang, Liuxin Jin, Zhenpeng Ma, Xuemei Zhai, Miao Yang, Wei Wang*, and Gerhard Wegner
keywords：Crystal pattern; Dendritic-to-faceted; Poly(ethylene oxide)
source：期刊
specific source：The Journal of Chemical Physics
Issue time：2008年

The detailed T_c-sensitive crystal pattern transition from dendrites through fourfold-symmetric structures to faceted crystals of ultrathin poly(ethylene oxide) films has been experimentally observed using atomic force microscopy. The transition has been quantitatively described by the T_c-dependences of the fractal dimension and of the velocity ratio caused by forward and transverse growths in crystal tips. The essential aspect of the pattern selection and transition is mainly the competition of two macroscopic mechanisms: Nucleation-limited and diffusion-limited growths which create faceted and dendritic crystal patterns, respectively. Their combination is a facet growth within a diffusion field which will create a faceted dendrite.