Mossbauer effect at Sn nuclei in fine crystalline MnO

The hyperfine structure of the low-temperature Mossbauer spectra of dopant Sn ions (0.4 at. %) in a fine crystalline MnO sample, characterized by X-ray diffraction and magnetic measurements, has been studied. The Sn spectra show that tin is distributed over positions with an inhomogeneous cationic environment. The appearance of such positions is explained by the local compensation for the excess charge of Sn by manganese vacancies V Mn and segregation of defects resulting in precipitation of MnSnO3 clusters. The non-uniform distribution of Sn and the related dependence of the number of broken magnetic bonds on the local tin concentration are responsible for the fluctuation of the T N values, which is 'perceived' by Sn in different MnO crystallites. The Sn spectra exclude the possibility that tin enters into the composition of superpara-magnetic particles.