Isotope Exchange of Gaseous Oxygen with Oxide LaMno3+δ Nanograins Boundary
Isotope exchange of oxygen 18О2 with the boundary of nanograins of oxide LaMnO3+ obtained by the method of shock-wave loading was investigated in the temperature range of 400 – 500 °C. It was established that the temperature dependence of the isotope exchange rate is described by the Arrhenius expression, the activation energy and the pre-exponential factor being 1.67 eV and 1.8∙102 cm/s, respectively. Comparison with literature data has shown that for oxide LaMnO3+, a significant difference in activation energies and pre-exponential factors is observed for the isotope exchange rate with a ‘defect-free’ surface and the nanograin boundary. In case of the boundary, these parameters were higher: the activation energy about two times, and the pre-exponential factor, by almost 7 orders of magnitude.
Andreas Öchsner, Graeme E. Murch, Ali Shokuhfar and João M.P.Q. Delgado
A. Y. Fishman et al., "Isotope Exchange of Gaseous Oxygen with Oxide LaMno3+δ Nanograins Boundary ", Defect and Diffusion Forum, Vols. 297-301, pp. 1301-1305, 2010