Crystal Research and Technology
Cryst. Res. Technol. 38, 143 (2003) - Abstract -

Atomic force microscopy studies on surface morphologies of CdHg(SCN)4 crystals grown in solutions containing excessive amount of Cd(II) cations

X. N. Jiang, D. Xu*, D. L. Sun*, D. R. Yuan*, Q. Y. Zhang

State Key Laboratory for Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Dalian 116023, People’s Republic of China
*State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan 250100, People’s Republic of China

Keywords    surface morphology, excessive Cd(II) cations, CMTC crystals, growth units, impurity, atomic force microscopy

Surface morphologies of CdHg(SCN)4 (CMTC) crystals grown from solutions with excessive amount of Cd(II) cations (5%, 20% and 50% in molar ratio) have been investigated by atomic force microscopy (AFM). [Cd(SCN)n]2-n (n<=4) complex anions formed by addition of excessive Cd(II) cations in the solutions have been found to act either as growth units or impurities during CMTC crystal growth. On the prismatic faces, incorporation of [Cd(SCN)n]2-n (n<=4) complex anions as growth units leads to the formation of well-oriented protuberance trains at the step fronts, named as “locally anisotropic crystal growth”. These protuberances become fewer, less distinct and nearly disappeared with the increase of excessive Cd(II) cations in the solutions. The pyramidal face, however, varies from regular 2D nucleation growth at a low concentration of Cd(II) to much rougher growth surfaces at high concentrations, exhibiting typical surface morphologies where crystal growth is completely inhibited by impurities. Observations in this experiment provide a new picture of crystal growth.



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