We require 1 day of rapid access time to complete the study of some novel catalyst materials based on doped CeO2. The work is for a final-year PhD student to make the link between the measure properties and atomic-scale structure of some novel oxides to understand the mechanism of activity of some functional materials with industrial application. We have already a set of Nb-doped CeO2 samples made in sodium hydroxide solution where the inclusion of Na+ provides a mechanism to balance charge; now we have samples made in ammonium hydroxide, from which ammonia can be driven off to leave active catalysts: the mode of charge balancing is not immediately obvious here but must be determined to explain their oxygen storage properties. We will use Reverse Monte Carlo analysis of total scattering date to build atomic-scale models consistent with all other data, which includes XRD, XANES and NMR.