Recent progress with titanate and silane coupling agents in the surface modification of inorganic fillers is reviewed. The coupling mechanisms and their effects plus some examples of their practical applications are described.
Very hard diamond like carbon films have been prepared by applying the ionized deposition technique, and the growth mechanism of the film in the case of methane gas is discussed. Properties of these carbon films obtained are as follows. Micro Vickers hardness dependis on the deposition conditions such as substrate potential, temperature, and ionization rate, but in some conditions, the hardness shows a larger value than that of silicon and sapphire. The resistivity and dielectric constant are close to those of diamonds. The electron diffraction pattern from the (111), (220), and (311) planes can be observed clearly, and the results show that the crystal structure calculated from these rings is very close to the diamond structure.
Thin Mo films were prepared on tho cleaved surfaces of NaCl using the electron beam evaporation and two deposition parameters of substrate temperature and film thickness. Abnormal structures appearing on the Mo film were then investigated by transmission electron microscopy and electron diffraction. An amorphous Mo film was formed independent of the thickness of the film at substrate temperatures below 150°C, but nucleation was observed to take place above about 100°C. At high substrate temperatures, also, abnormal fcc and/or fcc+bcc structures in the Mo films were formed when the film thickness was below about 16.9nm. For film thicknesses above 16.9nm, all the deposited films had normal bcc structure for bulk Mo. Electron micrographs and electron diffraction patterns revealed that the Mo films, including fcc phase, had both microcrystallities and two dimensional growth layers growing epitaxially on the (100) surfaces of NaCl held at 400°C.
Electronic structures of oxide surfaces are discussed based on the results of recent DV (Discrete-Variational) -Xα cluster calculations. Surface electronic structures of oxide crystals with mixed ionic and covalent attributes are achieved by the following : A) reduction of the Madelung potential compared to the bulk, B) strong field on the surface ionic site and the distortion of the ionic orbitals, C) the lack of orbital mixing between the surface ions and its nearest removed counter ions, and D) the reduction of the ionicity of surface ions and the enhanced covalency on the remaining bonds around it. The localized electronic states associated with surface defects are clarified and their significance to surface chemical activity is discussed. The origin of the compensating charge of the polar surfaces is made clear and their peculiar electronic properties are studied.
Infrared and Raman spectroscopic methods for surface studies using photon probes are reviewed briefly. Infrared techniques offer the possibility of measuring at high resolution over a wide pressure range. This technique also has a particular advantages since infrared light sources do not influence or disturb the absorbed layer. Laser Raman spectroscopies are useful methods because there are no restritions as to the accessible frequency range (50 to 4, 000cm-1) or the ambient gas pressure (one atomosphere to UHV). The technique is unique in its ability to obtain vibrational data for adsorbed species at the water-solid interface. In the future, these spectroscopical techniques will undoubtedly be applied to the study of in-situ chemical reactions on well defined metals as well as electrode surfaces.