Raman Spectrometric Determination of the Oxygen Self‐Diffusion Coefficients in Oxides

Abstract

New methods of determining the oxygen self‐diffusion coefficients (D*o) in oxides have been developed using Raman spectroscopy combined with the 16O–18O exchange technique. From the depth‐profiles of the 18O concentration in the 16O–18O exchanged oxides, which was measured by Raman microscope with a spatial resolution of 5 μm, D*o was determined for 2.8 mol% Y2O3‐containing tetragonal zirconia polycrystall (the depth‐profile method). Thus‐obtained results are expressed as D*O,D‐P= 1.82(+0.41−0.40) × 10−1·exp{−(139.3 ± 0.2) [kJ/mol]/RT} [cm2/s] in the temperature range of 700–950°C. We also determined D*o for the same sample from the Raman spectrometric monitoring of the ambient gas during the 16O–18O exchange reaction (the gas‐monitoring method). Thus‐obtained results are expressed as D*O,G‐M= 1.14(+0.05−0.04) × 10−2 exp{−(117.5 ± 0.4) [kJ/mol]/RT} [cm2/s] in the temperature range of 700–1165°C. The results obtained from the above two different methods virtually agree with each other, indicating that reliable D*o can be obtained by either of these two methods. We demonstrate that Raman spectroscopy is a useful tool for determining D*o in oxides.