Modification of chemical properties by ion beam mixing techniques

Abstract

Important chemical surface properties which may be modified by ion beam techniques are the resistance against oxidation and corrosion and the catalytic activity. Many studies using ion implantation showed in the past its potential for improving and understanding chemical reactions at the surface of materials. However, in most cases the surface concentration of implanted atoms was not high enough to obtain the desired effects and to maintain them for a longer period of time, respectively. Ion beam mixing and especially ion beam assisted deposition (IBAD) improve this situation greatly. With both techniques impurity concentrations up to 100 atom% can be introduced in the surface region of any material. With IBAD well adhering surface layers consisting of elements or compounds up to 10 μm thick may be produced. In this contribution ion beam mixing techniques are reviewed, and recent results of chemically oriented studies are presented. The examples will deal with heterogeneous catalysis in the liquid phase, protection against aqueous corrosion and high temperature oxidation. Metals and ceramic substrates will find consideration.