Investigations of the quadrupole interactions in the CnO cation sites by means of the Fe-57(3+) and Fe-57m(3+) Mossbauer probes

Both the isolated Fe-57m(3+) centers in the cation sites and the associatio ns of Fe-57(3+) with cation vacancies have been found in CuO by means of em ission and absorption Mossbauer spectroscopy. A satisfactory agreement of c alculated and measured values of the quadrupole splitting was obtained for the isolated Fe-57m(3+) centers if the electric field gradient (EFG) at the Fe-57m nuclei had been assumed to arise from the lattice ions only. For th e associates, the EFG calculations proved to be incorrect under the above a ssumption because of uncontrolled EFG sources.