J. J. Bara

Hyperfine interactions and crystal site occupancies in RTiFe11−xCox (R=Y, Dy and Er) as seen by Mössbauer spectroscopy

Abstract RTiFe 11− x Co x (R=Y, Dy, Er) systems have been studied by 57 Fe Mossbauer spectroscopy at 295 and 78 K. The composition dependencies of hyperfine interaction parameters and the relative occupancies of Fe crystal sites by Co atoms were derived from the spectra. It was found that Co atoms strongly avoid the 8i sublattice and strongly prefer the 8f and 8j sites for the three studied systems. Some anomalies in behaviour of the quadrupole interaction were observed for ErTiFe 11− x Co x system which can be attributed to spin reorientation transition.

Distributions of the hyperfine interaction parameters in (Er1−xSmx)2Fe14B as seen by Mössbauer spectroscopy

Abstract The distributions of the hyperfine interaction parameters, caused by substitution of Sm for Er in the (Er1−xSmx)2Fe14B system, were studied by Mossbauer spectroscopy both at room and liquid nitrogen temperatures. It was proved that the random distribution of the rare earth atoms over their crystal sites and the additive contribution of the Sm atoms to the values of the hyperfine interaction parameters at the iron crystal sites lead to a linear dependence of the average values of the 57Fe hyperfine magnetic field, isomer shift and quadrupole interaction on the Sm concentration in the present compounds. From these linear relations, the contributions ΔH, ΔIS and ΔQS to the values of the hyperfine magnetic field, isomer shift and quadrupole interaction, caused by the presence of the Sm atom in the nearest neighbour shell of the Fe crystal sites, were derived. No distinct correlations were found between the ΔH, ΔIS and ΔQS values and those of the nearest neighbours and/or their distances from the Fe crystal sites.