Raman Investigation of the Nitridation of Yttria-Stabilized Tetragonal Zirconia

Raman spectroscopy has been used to obtain Raman spectra of yttria-stabilized tetragonal zirconia subject to surface nitridation induced by contact with zirconium nitride. Raman spectra recorded from regions at increasing distance from the source of nitridation have been used to obtain diffusion profiles from samples treated at different times and temperatures. The coupling of X-ray diffraction data previously taken and of the Raman spectra shows that in the samples there is a two-phase region (tetragonal + cubic) near the nitrided surface and that, at larger distance inside the samples, there is only one phase (tetragonal). Fitting of the diffusive profiles in the single-phase tetragonal region with an appropriate diffusion function allows the determination of the diffusion coefficient of nitrogen in tetragonal zirconia which is expressed in terms of the preexponential factor, D ₀= (3.98 ± 0.5) × 10⁻³ cm²/s, and the activation energy, Q = 170 ± 10 kJ/mol.