Mössbauer Spectroscopy of Iron Implanted in Zirconia

Zirconium oxide Zr02, as an important representative of advanced ceramic materials, has outstanding mechanic, refractory, and electrochemical properties. In addition to its wide use in ultra-strong stabilized zirconia tools and as an ion conducting electrolyte in oxygen sensors, pumps, and fuel cells, it has recently been examined for use in ceramic automotive engines and as a support for high temperature catalysts (1,2). Zirconia plays also a crucial role in nuclear reactors as a protective oxide layer on various zirconium-alloy components, such as fuel cladding, fuel channels and pressure tubes. It appears that iron impurities in zirconia may seriously affect the properties of the zirconia-based ceramics as well as the oxida¬tion characteristics of zirconium alloys (3–5). However, unlike the Zr-Fe alloy system, which is rather well established (6), the knowledge of the ternary Zr-Fe-0 system is still in its infancy (7,8). Therefore, detailed understanding of the state of iron in zirconia, and — particularly — its role in oxygen and hydrogen transport, is of primary interest.