ZnO and GaN, two possible candidates for dilute magnetic semiconductors, have been studied with time-differential perturbed angular correlation (PAC) spectroscopy using the probe 100Pd/100Rh. The probe was produced using the fusion evaporation reaction 92Zr(12C, 4n)100Pd at a beam energy of 70 MeV and introduced into ZnO and GaN samples via recoil implantation. Annealing does not lead to unique probe environments, effectively excluding that a significant fraction of probes is substitutional on undisturbed lattice sites. This is in marked contrast to the behaviour of 111In/111Cd in these two compound lattices. For ZnO 45% of the probes may be substitutional, however, they are in strongly disturbed locations. Further measurements have excluded the possibility that the PAC results are affected by internal magnetism.