Nanostructure and strain analysis of CeO₂/YSZ strained superlattice

In this study, the nanostructure and the strain fields in the superlattice [CeO₂/YSZ]₅ fabricated on the SiO₂/Si(0 0 1) substrate were investigated macroscopically and nanoscopically using X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) with geometric phase analysis (GPA) and related methods. The XRD analyses elucidated that the out-of-plane lattice parameter of CeO₂ and YSZ layers is relaxed. However, the in-plane lattice parameter is almost identical. Results of HRTEM and related analyses revealed that CeO₂ and YSZ layers form a superlattice structure. Results show that the superlattice has some defect structure, such as misorientation, varied thickness of CeO ₂ and YSZ layers, varied artificial periodicity, and interface roughness. However, the out-of-plane lattice parameter has periodicity corresponding to the superlattice structure. The in-plane lattice parameter is also equal to the local deviation. Therefore, the strain effect in the superlattice persists to some degree.