In situ X-ray diffraction studies of Ce0.9Y0.1O2-δ, Ce0.65Pr0.25Y0.1O2-δ and Pr6O11
Ce0.9Y0.1O2‑δ(YDC), Ce0.65Pr0.25Y0.1O2‑δ(YPDC) and Pr6O11 were synthesized by Pechini technique and sintered at 1100°C. The samples were characterised by X-ray diffraction (XRD) and TEM methods.
It has been found that oxides behave differently after change of the ambient oxygen partial pressure (pO2). In situ XRD experiments showed that YPDC cell reversibly expands after change to the lower pO2 at 500-600C due to the oxygen loss while YDC didn't show any significant structure changes. For the Pr6O11 the following structure changes were observed at the same conditions: monoclinic → cubic → trigonal.
We also estimated the oxygen mobility coefficients(kchem - oxygen surface exchange coefficient and Dchem - oxygen chemical diffusion coefficient) of all samples by analysis of the cell volume relaxation (CVR) curves obtained from the XRD data after abrupt change of the oxygen partial pressure from 100 mBar to 10 mBar. Since no relaxation was observed for YDC, kchem and Dchem could not be calculated. For YPDC process is limited by surface exchange thereby only kchem could be calculated. The following kchem values were determined for YPDC 1.310^(-4) cm/s at 500 °C and 1.610^(-4) cm/s at 600 °C. For Pr6O11 both kchem and Dchem could be calculated simultaneously and were about 5.0·10^(-4) cm/s and 5.0·10^(-7) cm^2/s at 500 °C.
In situ XRD experiments were carried out with involvement of equipment belonging to the shared research center “SSTRC”.