The Study Of Metal-oxide Interfacial Structure By Electron Microscope And The Application Of Electron Dynamic Diffraction

Metal-oxide interfaces are of major importance for many advanced materials, sometimes, they play a key role for some special materials such as functional ceramics with metals, oxide dispersion-strengthened alloys, oxide coatings on metals, catalysts etc. It is well known that the macroscopic properties of materials are decided by their microstructures. In order to improve the properties of materials, one needs to understand the structural relationship between interface and matrix of the materials, such as interface atomic structure, misfit dislocation, chemical bond structure, stress field distribution, composition segregation etc.There are tremendous research works on the grain boundary and interface structures during last century and the sophisticated theory about grain boundary and interface, i.e. coincidence site lattice and 0-lattice theories had been developed simultaneously. However the study of metal-oxide hetero-interface is relatively less because the properties of metals and oxides usually differ extremely from each other. Contrary to metals, the oxides are usually very brittle, elastically stiffer, insulating and exhibit less thermal expansion and their crystal lattice constants are different from metals. Moreover, the preparation of specimen of metal-oxide interface is very difficult, the observation of searching a suitable interface under the electron microscope is also a tedious work.Fortunately, we have succeeded to prepare Cu-MgO interface specimen by internal oxidation. A plenty of different orientations with different interfaces between Cu and MgO have been observed andselected by TEM. The orientation relationships between Cu and MgO are determined by means of electron diffraction patterns. The interface structures are analyzed according to high-resolution images of TEM, CSL and 0-lattice theories and verified by simulation computation method.New methods of measurements of specimen thickness and non-elastically scattering mean free path are proposed based on the electron holograph combining with electron dynamic diffraction.