Effect of surrounding environment on atomic structure and equilibrium shape of growing nanocrystals: gold in/on SiO2

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 SiO2surface or embedded in SiO2layer. Quantitative data on the NCs surface free energy were obtained via the inverse Wulff construction. Nanocrystals inside the SiO2layer are defect-free and maintain a symmetrical equilibrium shape during the growth. Nanocrystals on SiO2surface 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 SiO2is 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

Producer Services Linkages in the Hong Kong-Pearl River Delta Region

In the past two decades there has been growing interest in the development of integrated acoustic sensors. Sensors based on bulk (BAW) [1,2] and surface (SAW) [3,4] were reported. Most of these sensors operate in a gaseous medium, although a few are used with liquids or solids, to determine concentrations of chemical and biological substances, as well as viscosity, acceleration, temperature, pressure, etc. Recently, Wenzel and White [5] have found out that flexural plate wave gravimetric sensors can have higher mass sensitivity at low operating frequencies (a few MHz) than the BAW or SAW counterparts. The lowest flexural (antisymmetric) Lamb mode, A0, was used for thin isotropic plates [5]. The thickness of the plates is much smaller than an acoustic wavelength