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Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Effect of surrounding environment on atomic structure and equilibrium shape of growing nanocrystals: gold in/on SiO2 | Nanoscale Res Lett 2007 2 240-247 DOI 10.1007 s11671-007-9058-4 NANO EXPRESS Effect of surrounding environment on atomic structure and equilibrium shape of growing nanocrystals gold in on SiO2 F. Ruffino C. Bongiorno F. Giannazzo F. Roccaforte V. Raineri M. G. Grimaldi Received 21 March 2007 Accepted 13 April 2007 Published online 8 May 2007 to the authors 2007 Abstract We report on the equilibrium shape and atomic structure of thermally-processed Au nanocrystals NCs as determined by high resolution transmission electron microscopy TEM . The NCs were either deposited on SiO2 surface or embedded in SiO2 layer. Quantitative data on the NCs surface free energy were obtained via the inverse Wulff construction. Nanocrystals inside the SiO2 layer are defect-free and maintain a symmetrical equilibrium shape during the growth. Nanocrystals on SiO2 surface exhibit asymmetrical equilibrium shape that is characterized by the introduction of twins and more complex atomic defects above a critical size. The observed differences in the equilibrium shape and atomic structure evolution of growing NCs in and on SiO2 is explained in terms of evolution in isotropic anisotropic environment making the surface free energy function angular and or radial symmetric asymmetric affecting the rotational translational invariance of the surface stress tensor. Keywords Nanocrystal Crystal growth Transmission electron microscopy Wulff plot Surface energy Gold SiO2 F. Ruffino M. G. Grimaldi MATIS CNR-INFM and Dipartimento di Fisica e Astronomia Universita di Catania via S. Sofia 64 95123 Catania Italy F. Ruffino El C. Bongiorno F. Giannazzo F. Roccaforte V. Raineri Consiglio Nazionale delle Ricerche - Istituto per la Microelettronica e Microsistemi CNR-IMM Stradale Primosole 50 95121 Catania Italy e-mail francesco.ruffino@ct.infn.it Introduction The discovery of nanostructures quantum dots nanoparticles quantum wires nanowires etc. have stimulated research in many different areas becoming the basis
