Ball milling of oxide blends can result in the formation of solid solutions depending on the characteristics of the oxides. In this paper the possibility of doping oxides with radioactive 181Hf through the formation of these solutions is analyzed. The 181Hf isotope decays to 181Ta, which is an adequate probe for perturbed angular correlations (PAC) studies. Through the measurement of the hyperfine interactions of 181Ta nuclei it is possible to determine the atomic distribution around the probes. We have thus studied the behavior of the La2O3-HfO2 ceramic system subjected to high-energy ball milling. An oxide blend, containing few atomic percent of hafnium oxide, was milled during several hours resulting in the formation of hafnium oxide defective phases. The sample was finally annealed at high temperatures in order to facilitate the formation of solid solutions. This thermal treatment produced a solid-state reaction given place to Hf2La2O7 pyrochlore and also the apparition of another phase or compound. The possibility of associating this last finding with a stabilized cubic phase of hafnium oxide resulting from lanthanum doping is analyzed. © 2009 Elsevier B.V. All rights reserved.