We propose a PDF/pXRD beamtime in which we want to investigate the role oxygen vacancy formation has on the exsolution of metallic nanoparticles (= migrating parts of the material to the surface, without destruction of the host, thus enhancing catalytic activity) in perovskite-oxides, a material used in heterogeneous catalysis and solid oxide fuel cells. By varying the A-site element of the material, we can tune oxygen vacancy formation which will be investigated by PDF. The pXRD measurements will allow us to characterise exsolution kinetics. These two experiments will give valuable insight into the material's properties and facilitate an intelligent design approach for novel catalysts and energy materials