Oxygen tracer diffusion in single crystalline yttrium silicate

Low resistance of C/C-SiC composites against oxidation at high temperatures created the need to develop materials that could be used as oxygen protective layers. Yttrium silicate (Y2SiO5) has been proposed as an excellent candidate for this purpose. In order to investigate whether Y2SiO5 is a sufficient barrier against oxygen, the transport parameters of oxygen in this material should be determined. In the present study, 18O2 tracer diffusion experiments have been conducted in the temperature range between 1000 °C and 1300 °C. Secondary ion mass spectrometry (SIMS) was used to determine tracer diffusivities D⁎ and oxygen incorporation rates k⁎ in undoped and in 0.3 at.% praseodymium doped yttrium silicate. Activation enthalpies EA(D⁎) and EA(k⁎) were determined. An indication of anisotropic oxygen diffusion in yttrium silicate has been found.