Considerable research has been devoted to materials to fulfil the roles of electrodes and electrolyte within SOFCs, with focus on the fluorite or perovskite crystal structures. These compounds require high operating temperatures to achieve high oxygen ion conductivity. This motivate studies of other systems, e.g. spinel structured oxides as they are poorly understood. Their oxide-ion conductivity does not make them serious rivals for technological applications, their study is important from a more fundamental point-of-view, to examine the structure-property relationships within these oxide-ion conductors and compare this with the more widely probed Lithium conducting spinels. It is important to investigate the short-range correlations between ions and the oxygen ion diffusion paths in order to understand the influence of cation vacancy formation on the oxygen ion conduction mechanism.