Stress Folds Of The Law And The Realization Of Large Area Ordered Structure

The ordered structures have large potential application value in materials preparation, in which the stress self-assembly based on the large area fabrication of ordered structure has attracted much attention due to its generality and practicality. In this thesis, two thermal stress systems were applied to obtain large area ordered buckling structure, i.e., the two-dimensional surface PDMS/Pt soft substrate stiff film system and the three-dimensional spherical Ag/SiO_x soft core stiff shell system. The large area ordered buckling structures were obtained on the two-dimensional surface system with the confinement of the boundary conditions through adjusting the thermal stress. Besides, the buckling structure agreeing with the mechanism discipline on the three-dimensional sphere was also obtained. The research offers some clues to fabricating regularly ordered templates for the materials science. Furthermore, in the process of fabricating ordered buckling structure, some related problems were also investigated, such as self-assembly of colloid crystal on the buckling template, the growth and morphology transformation of silver crystal and so on. The mentioned above will be listed below separately.1. Large area ordered buckling structures were obtained on the PDMS/Pt soft substrate stiff film double system through the thermal stress. In order to study the formation discipline of the buckling structure, the irregular buckling structure was fabricated on the PDMS surface without decorated patterns. The relationships between the wavelength, amplitude and the thickness of the film, the heat treatment temperature were studied. In order to obtain ordered buckling structure, the formation and orientation of the buckling structures on the decorated PDMS were investigated. It is concluded that the boundary conditions play an important role in the buckling formation. In addition, the size, distance and arrangement of the patterns also have some influence on the formation and orientation of the buckling structure. In order to obtain one-dimensional ordered parallel buckling structure, the stretching and glass capillary methods were also adopted, in which the buckling wavelength could be adjusted through changing the stretching stress and the curvature of the glass capillaries.2. The colloid crystal was self-assemblied on the obtained buckling structure. The experiment result exhibited that the colloid crystal particles with different dimensions and layers could regularly arrange on the wave trough of the buckling sturcture by adjusting the suspension concentration. Furthermore, the CD and DVD discs are very good templates. Consequently, we had a try to self-assemble colloid crystal on these templates and obtained colloid crystals with one- and double-line particle arrangement.3. The Ag/SiO_x core shell structure was obtained through thermal co-evaporation of the mixture of Ag₂O and SiO, and the surface of the core shell structure could buckle under the thermal stress through governing the experiment parameter. It was found that the irregular Zigzag or herringbone buckling structures just like in the flat surface system can appear when the curvature of the core shell structure is relative smaller, whereas the triangular tessellation can be obtained on the relative larger curve surface. In addition, the SiO_x is fractural structure growth when creeping on silver sphere. Silver core with different curvature and silicon oxide with different thickness will result in diverse morphologies of buckling. The flower-like Ag/Si/SiO_x structures were also obtained through changing the amount of SiO. It consists of the up-part Ag/SiO_x core shell structure and the Ag/Si/SiO_x sheath structure. The research of the growth mechanism can deepen the understanding of the traditional VLS and OS growth mechanisms.4. The single and twin silver crystals were obtained through thermal evaporation of Ag₂O or the mixture of Ag₂O and SiO. For single crystal, various intermediates from polyhedral to nearly spherical crystal were obtained and the morphology transformation mechanisms from regular tetrahedron and octahedron to sphereical crystal had been figured out. The evaporation temperature and impurity effect of SiO_x play a key role in the morphology transformation of silver crystal. In addition, it is also a process that the high-index facets appear gradually. For twin crystal, the decahedron and icosahedron twin crytals were obtained in which the maximum diameter of icosahedron particle is 3μm. It is found that the nucleation of multi-twin silver crystal is in the cluster stage and the distributions of the intrinsic stress and the corresponding defects play a signification role in the growth of the silver twin crystal.