Mössbauer characterization of 119Sn 4 + Dopant ions in the antiferromagnetic ilmenite NiTiO 3

Abstract

Magnetic hyperfine splitting of the 119Sn 4+ nuclear levels in the antiferromagnetic NiTiO 3 was for the first time observed using the Mössbauer effect. For the majority of the 119Sn 4+ dopant ions, the saturation value of the transferred hyperfine field (at 4.2 K, H = 5.25 T ) is found to be equal to that previously reported for 119Sn 4+ in the antiferromagnetic MnTiO 3. This finding shows that in both ilmenites the spin polarization of Sn 4+ is produced by the divalent cation half-filled e g 2 orbitals involved in interlayer superexchange interactions and implies the location of the dopant within titanium (111) layers. The principal V z z component of the EFG at the Sn 4+ site in NiTiO 3 is found to have a positive sign and be aligned along the [111] axis, as it was the case for Sn 4+ in MnTiO 3. Lattice-sum calculations on the basis of a simple ionic point-charge model, lead to an erroneous result (in either titanate the sign of V z z on the Ti 4+ site would be negative) and thus demonstrate their failure in identifying the Sn sites.