Surface and grain-boundary energies as well as surface mass transport in polycrystalline CeO 2

Abstract

The multiphase equilibration technique for the determination of the equilibrium angles that develop at the interphase boundaries of a solid–liquid–vapor system, has been used to calculate the surface and interfacial energies in polycrystalline CeO 2 and CeO 2/Cu system in argon atmosphere at the temperature range 1473–1773 K. Linear temperature functions were obtained by extrapolation, for the surface energy γ sv (J/m 2) = 2.465–0.563 × 10 −3 T and the grain-boundary energy γ ss (J/m 2) = 1.687–0.391 × 10 −3 T of the ceramic, as well as for the interfacial energy γ sl (J/m 2) = 2.623–1.389 × 10 −3( T −1356 K) of the CeO 2/Cu system. Grain-boundary grooving studied on polished surfaces of CeO 2 annealed in argon atmosphere at the same temperature range has shown that surface diffusion was the dominant mechanism for the mass transport. The surface diffusion coefficient can be expressed according to the equation D s (m 2/s) = 3.82 × 10 −4 exp(−308,250/ RT).