Mößbauer-spektroskopische Untersuchungen am System Fe1+xSb mit NiAs-Struktur/ Mössbauer-spectroscopy in the system Fe1+xSb with NiAs-structure

Abstract

Measurements in the system Fe1+xSb for 0.13 ≦ x ≦ 0.30 and in the temperature range 10 K ≦ T ≦ 625 K are represented. In the paramagnetic phase one observes a small quadrupole splitting of ΔνQ=0.272 (8) mm/s, independent of the non-stoechiometric portion x. From the temperature dependence of the isomeric shift δ a Debye-temperature θ= (766 ± 100) K was determined. Néel temperatures are found to be about 211 K, varying smoothly with x, according to an increased number of bipyramidal FeII-atoms and therefore a stronger influence of the ferromagnetic coupling with octaedral FeI-atoms. The measured Mössbauer spectra in the antiferromagnetically ordered phase can only be interpreted as a superposition of several magnetic line-sextets, probably due to a variation of the local magnetic field at the site of 57Fe, with different numbers of nearest Fe-atoms. An exact assignment of the analysed fields to the number of nearest Fe-atoms was not possible. The magnetic saturation fields are in between 95 kG and 155 kG increasing with x. The direction of the local fields are found to be parallel to the plane (001) of the NiAs-lattice.