In this experiment, we intend to clearly separate the effect of the electronic interaction leading to the hyperfine interaction from that of the muon diffusion in the relaxation of the diamagnetic component observed in zirconia. Measurements in ultra-pure zirconia and scandium-stabilized zirconia are proposed in order to disentangle the effects of the concentration of oxygen vacancies and trapping on the diffusion, respectively. The known grain size effect in yttrium stabilized zirconia will be addressed by investigating two samples with 13 nm and 100 nm grain sizes.