“…From the Raman spectrum, all samples had a weak absorption band at 245 cm −1 , which could be attributed to a double degenerate transverse optical mode (Li et al, 2009). In addition, the Raman peak around 465 cm −1 was associated with the F 2g vibrational mode of the cubic lattice, indicating that the CeO 2 -based electrolytes still maintain the perfect cubic fluorite structure (Nakajima et al, 1994;Li et al, 2020;Song et al, 2021), which was consistent with the XRD results. Moreover, the positions of the vibrational peaks around 465 cm −1 for GDC-M and GDC samples were consistent, basically.…”