Diffusion-Controlled Creep in Mixed-Conducting Oxides

Abstract

The steady-state creep rate of mixed-conducting oxides, Lal_,SrxMn03, for x = 0.1,O. 15, and 0.25, and Lao.7Ca0.3Mn03 has been investigated at temperatures between 1150 and 13OOOC. Creep parameters and transmission electron microscopy observations indicate that deformation is controlled by lattice diffusion of one of the cations. The dependence of the creep rate on Sr concentration, combined with a point-defect model, confirms this hypothesis; however, the oxygen partial pressure dependence of creep (from 10-1 to 2 x 104 Pa) cannot be accounted for within the framework of a simple poin t-de fec t model.

Oxygen Isotope Exchange between Gaseous Phase Enriched with ¹⁸O Isotope and Nanocrystal Oxides LaMnO_3+δ Obtained by Severe Plastic Deformation

“…It was interesting to compare our volume diffusion coefficient with the result of direct diffusion measurements. The corresponding literature data are available for strontium-doped LaMnO 3 -based perovskites at temperatures of 700-977 [8][9][10]. Strontium has little effect on the volume diffusion coefficients of oxygen tracers [11].…”

A Monte Carlo simulation of B-site order disorder transformation in Pb(Sc1/2Ta1/2)O3triggered by mechanical activation

“…The order-disorder transformation is similar to that in FeAl alloys, which was demonstrated by Pochet et al [9], whose experimental observation and theoretical prediction suggested that such a transformation can be ascribed to the competition between thermal diffusion and mechanically induced shearing and glides [11]. Although extensive shear-induced glides may not commonly occur in bulk oxides, they have been observed in perovskite structures at elevated temperatures, and in particular in some nanocrystalline oxides, which exhibit a considerable degree of superplasticity and glide-induced behaviours [24][25][26]. Furthermore, the in situ temperature at the collision point can be very high [3].…”

Oxygen Isotope Exchange in Nanocrystal Oxides

“…2) obtained from C(t) dependences processing also proved to be quite reasonable. For strontium-doped LaMnO 3 -based perovskites, experimental oxygen volume diffusion coefficients are available in the literature for higher temperatures (Carter et al 1992;De Souza et al 2000;Fishman et al, 2003;Routbort et al, 1997). Strontium was not found to have any profound effect on the volume diffusion coefficients of tracer oxygen atoms (Fishman et al, 2003).…”