Oxygen self-diffusion in cerium oxide doped with Nd

Abstract

Polycrystalline Ce0.77Nd0.23O1.885having a relative density in excess of 98% was prepared. Oxygen diffusion experiments were performed for the temperature range from 750 to 1100 °C, in an oxygen partial pressure of 6.6 kPa. The concentration profile of18O in the specimens following diffusion annealing was measured by secondary ion mass spectroscopy (SIMS). The oxygen self-diffusion coefficient obtained using secondary ion mass spectrometry was expressed by D = 6.31 × 10−9exp(−53 kJ mol−1/RT) m2s−1and was in the extrinsic region. The oxygen diffusion coefficient of Ce0.77Nd0.23O1.885was larger than that of Ce0.8Y0.2O1.90; it was close to those of Ce0.6Y0.4O1.80and Ce0.69Gd0.31O2−δ. The oxygen diffusion coefficient obtained by the tracer method at 700 °C agreed with that calculated from the electrical conductivity in Ce0.77Nd0.23O1.885. The activation energy of the surface exchange coefficient was 94 kJ mol−1, and the values of the surface exchange coefficient were similar to those of stoichiometric CeO2and ThO2.