The CoO/Co3O4 phase transition studied by PAC

The hyperfine environment of¹¹¹Cd nuclei formed in the radioactive decay of¹¹¹In ions implanted into CoO was studied via the PAC method. The quadrupole coupling constants measured in isochronal and isothermal annealing treatments at various oxygen pressures were related to the initial stages of the CoO→Co₃O₄ phase transition and interpreted as the successive trapping of cation vacancies at the¹¹¹In probe. The phase transition was confirmed by X-ray diffraction, RBS and a PAC measurement on¹¹¹Cd in spinel type Co₃O₄.