| The unique properties of SiC (wide band gap, high thermal conductivity, high electron mobility, and resistance to radiation effects) permits it to operate reliably at very high temperatures even in harsh environments and as coating layers in TRISO nuclear fuels. To optimize the SiC for use as a coating material in the nuclear reactor fuel design, it is important to elucidate the chemical bonding and interface formation of metal fission products (Pd, Ag, Cs, etc.) with SiC coating layers and to study the diffusion behavior of fission products into TRISO coating materials. It is known in the TRISO community that Pd is able to corrode the SiC layer. However, the detailed nature of this corrosion is still unknown.; The objective of this thesis is to study the influence of fission products (Pd) on the chemical and electronic properties of the SiC coating layer in TRISO nuclear fuel particles. For this purpose, three series of interfaces (Pd/SiC) were prepared and studied using X-ray Photoelectron Spectroscopy (XPS) and Ultraviolet Photoelectron Spectroscopy (UPS).; The experimental approach comprises the preparation of Pd/SiC interfaces in-situ in our ultra-high vacuum system by electron-beam deposition of Pd onto suitable prepared SiC single crystal surfaces. In order to understand the impact of the SiC surface properties on the interface formation, a variety of surface preparation and modification schemes were employed. The results obtained give detailed information about the Pd/SiC interface formation. Thereby the study shows a diffusion at this interface, which is an important first step in understanding the corrosion of the SiC-layer in the TRISO particles. |
