Surface and grain-boundary energies as well as surface mass transport in polycrystalline CeO2

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 CeO2 and CeO2/Cu system in argon atmosphere at the temperature range 1473-1773 K. Linear temperature functions were obtained by extrapolation, for the surface energy gamma,v (J/m(2)) = 2.465-0.563 x 10(-3) T and the grain-boundary energy gamma(ss) (J/m(2)) = 1.687-0.391 X 10(-3) T of the ceramic, as well as for the interfacial energy gamma(sl) (J/m(2)) = 2.623-1.389 x 10(-3)(T - 1356 K) of the CeO2/Cu system. Grain-boundary grooving studied on polished surfaces of CeO2 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 x 10(-4) exp(-308,250/RT). (C) 2008 Elsevier B.V. All rights reserved.