Study of Raman peak shift under applied isostatic pressure in rare-earth-doped ceria for evaluation of quantitative stress conditions in SOFCs

We studied the relation between the Raman peak shift of the ceria F _2g peak and isostatic pressure in rare-earth-doped ceria, which is used as interlayer in anode-supported SOFCs, to evaluate the stress in operational anode-supported SOFCs. First, 10 and 20 mol% Sm- and Gd-doped ceria, and pure ceria were isostatically compressed up to 10 GPa in a diamond anvil cell and the Raman spectra were measured at each pressure. Based on the results and reported elastic properties, the relation was retrieved for rare-earth-doped ceria under anisotropic stress. Although rare-earth-doped ceria showed different behavior than pure ceria, the difference due to the dopant and its concentration was small. The obtained ratio between anisotropic pressure and Raman peak shift in rare-earth-doped ceria was 0.441 GPa/cm ^{- 1}, and this value indicates that a change of 1 GPa in anisotropic stress will shift the Raman peak by approximately 2.3 cm ^{- 1}. Hence, a Raman system, which can measure the Raman peak shift with an accuracy of 0.1 cm ^{- 1}, can recognize differences in stress conditions in the interlayer to an accuracy of approximately 40-50 MPa.