Xenon bubbles formed by ion implantation in zirconium alloy films

The xenon content of a Zircaloy-4 thin film was quantified in a spatially resolved way using high angle annular dark field (HAADF) images and DualEELS, a type of electron energy loss spectroscopy that takes spectra from the high- and low-loss regions in quick succession. The xenon in the films was implanted using a tandem accelerator. The HAADF images show that the xenon had coalesced into bubbles. A semi-empirical standard was used created for the quantification using pre-existing xenon data and experimental data scaled using a Hartree Slater cross-section. This standard was used to calculate the number of atoms in the xenon bubbles and their densities and pressures were then calculated. In total, 244 were bubbles were analysed. The mean diameter, density and pressure across all the bubbles were 21.2 Å, 2355 kg/m and 5.27 GPa respectively. Most of the bubbles were gaseous xenon. The separation of the bubbles was also analysed. This work is a good demonstration of a characterisation technique for end-of-life structural materials and the technique can be easily applied to small gas bubbles in other materials