Abstract
Raman spectroscopy is applied for non-destructive characterization of strain in crystalline thin films. The analysis makes use of the numerical value of the mode Gruneisen parameter gamma, which relates the fractional change in the frequency of a Raman-active vibrational mode and the strain-induced fractional change in the unit cell volume. When in-plane, compressive biaxial strain in aliovalent doped CeO2-films is relieved by partial substrate removal, the films exhibit values of gamma for the F2g vibrational mode which are similar to 30% of the literature values for bulk ceramics under isostatic stress. This discrepancy has been attributed to a negative contribution from the anelastic (time-dependent) mechanical properties of aliovalent-doped ceria. Here we propose a way to "separate" anelastic and elastic contributions to the F2g mode Gruneisen parameter. Mechanically elastic yttria (Y2O3) films on Ti/SiO2/Si substrate serve as "control". The values of gamma calculated from the change in frequency of the similar to ∼375 cm-1 F2g Raman-active mode are close to the literature values for bulk yttria under isostatic stress. This work should serve to provide a protocol for characterization of selective sensitivity to different strain components of doped ceria thin films.
| Original language | English |
|---|---|
| Pages (from-to) | 30563-30571 |
| Number of pages | 9 |
| Journal | Physical Chemistry Chemical Physics |
| Volume | 25 |
| Issue number | 44 |
| Early online date | Oct 2023 |
| DOIs | |
| Publication status | Published - 15 Nov 2023 |
Funding
This work was supported by the PAZY foundation grant #2018/57. This work made possible in part by the generosity of the Harold Perlman Family and was in part supported by the Minerva Center for Self-Repairing Systems for Energy & Sustainability.