C. Munnings

Electrical properties of iron-substituted La6.4Sr1.6Cu8O20±δ

Abstract The electrical properties of a series of perovskite-related cuprates have been investigated at elevated temperatures with a view to using these types of materials as solid oxide fuel cell cathodes. In this study, the compositions La 6.4− x Sr 1.6+ x Cu 8− x Fe x O 20± δ where 0≤ x ≤2 are investigated as a preliminary study to investigate the feasibility of developing these materials as cathodes. The materials reported here have a peak conductivity at 300 K of 1.46×10 3 S cm −1 for the undoped material dropping to 5.0×10 2 S cm −1 at 1043 K. This is well above the minimum requirement for a cathode material and suggests that further investigation is warranted.

Tetragonal CeNbO4 at 1073 K in air and in vacuo

The structure of the high-temperature scheelite-type polymorph of cerium niobium tetraoxide, CeNbO(4), has been determined using time-of-flight neutron powder diffraction data collected both in situ at 1073 K in air and in vacuo. In both cases, the structure was found to be tetragonal, with I4(1)/a symmetry and without any significant deviation from the stoichiometric composition.

Oxide Ion Transport in Novel K2NiF4-Type Oxides

Single-phase La2Ni0.5Co0.5O4+δ has been prepared by the Pechini method. The oxygen tracer diffusion coefficients, D*, were determined with isotope exchange and secondary ion mass spectrometry (IEDP-SIMS) over the temperature range 470°C-750°C. An unusual change in the activation energy from ~40 KJ mol-1 to ~20 KJ mol-1 at 600°C is observed and is ascribed to a possible change in the oxide_ion conduction mechanism.