Abstract
A totally new molecular beam method for the production of a barrier films on metal surfaces has successfully been developed. The method developed is capable of the deposition of mixed oxide barrier films on an atomic layer-by-layer basis. This enables the films to be grown to any desired thickness. The films produced, whilst being very thin (less than 20A) have a particularly dramatic effect on interdiffusion between metallic phases. The XPS analysis and the electrochemical test confirmed that the films are uniformly deposited and non-porous. Thus they are believed to be of considerable impox-tance for the development of advanced materials. A further development of the process which should facilitate its use on continuous lengths of fibre or sheet material e.g. metal wire and carbon-fibre tow, has also successfully been undertaken. The in situ deposition carried out in this work has produced clean and fresh films of chlorides and been able to eliminate the problem of surface deterioration. Having this, the opportunity was taken to investigate the development of themsatellite structure on the 2p peaks in the photoelectron spectra of the 3d transition metal(II) chlorides, over the whole range from CrCl2 to ZnCl2 . New features and increased detail of the 2p photoelectron satellite lines have been obtained in the course of this work. The success of the advanced material is dependent upon the ability to control the reaction between the materials used in the system. This dependence places a severe limitation on the combinations of materials that may be used. One way of overcoming this limitation is by coating the material with a corrosion resistant or passive barrier film. This thesis describes a technique for the production of a mixed oxide film of Cr(III) and Fe(II ) by using molecular beams of Cr (III) chloride, Fe(II) chloride and H2O. The technique developed is capable of the deposition of the film on an atomic layer-by-layer basis. The growth process and the properties of the film which are desired for advanced materials were studied. XPS was the main analytical tool in many stages of this work. The information contained in the XPS which comes from the first four to five atomic layers at the surface of the sample has provided the opportunity to follow and examine the development of the film. The mixed oxide films produced are capable of inhibiting interdiffusion between metallic phases. They also permit the conduction of electrons. The XPS analysis and the electrochemical test confirmed that the films are continuous and non-porous. The in situ deposition carried-out in this work has produced clean and fresh films of chlorides and been able to eliminate the problem of surface deterioration. Having this, the opportunity was taken to investigate the development of the satellite structure on the 2p peaks in the photoelectron spectra of the 3d transition metal(II) chlorides, over the whole range from CrCl2 to ZnCl2. New or increased detail of the 2p photoelectron satellite lines has been obtained in the course of this work.