Study of the mechanical properties of CeO2 layers with the nanoindentation technique

The mechanical properties of CeO2 layers that are undoped or doped with other elements (e.g. Zr and Ta) are a topic of special interest specially in the manufacturing of superconductor buffer layers by pulsed electron deposition. Nowadays, the trend is to produce small devices (i.e. coated conductors), and the correct mechanical characterization is critical. In this sense, nanoindentation is a powerful technique widely employed to determine the mechanical properties of small volumes. In this study, the nanoindentation technique allow us determine the hardness (H) and Young's modulus (E) by sharp indentation of different buffer layers to explore the deposition process of CeO2 that is undoped or doped with Zr and Ta, and deposited on Ni–5%W at room temperature. This study was carried out on various samples at different ranges of applied loads (from 0.5 to 500 mN). Scanning electron microscopy images show no cracking for CeO2 doped with Zr, as the doping agent increases the toughness fracture of the CeO2 layer. This system, presents better mechanical stability than the other studied systems. Thus, the H for Zr–CeO2 is around 2.75 · 106 Pa, and the elastic modulus calculated using the Bec et al. and Rar et al. models equals 249 · 106 Pa and 235 · 106 Pa respectively.