Study on velocity mode of 57Fe Mӧssbauer spectroscopy and determination of lattice dynamics in Fe3S4

Abstract

57Fe Mӧssbauer spectroscopy studies on chemically synthesized greigite Fe3S4 have been conducted with a unique velocity mode, known as constant velocity with slope, which allows detection of subtle changes and in-depth details of sextets in the spectra. Accurate determination of the overlapped sub-spectra corresponding to tetrahedral Fe3+ (A) and octahedral Fe2.5+ (B) sub-lattices has been made based on the special velocity mode. Estimation of Debye temperature θD from the temperature dependent central shift (CS) values gives the values: 805 ± 10 K and 760 ± 10 K for A- and B-sites, respectively. The discrepancy of two θD values reveals different lattice vibration between A- and B-sites. The Lamb-Mӧssbauer factor ratio fB/fA is found to be 0.98 at room temperature. The different low-temperature behaviors of hyperfine magnetic field for tetrahedral A- and octahedral B-sites are observed. Keywords: Spinel structure, Mӧssbauer, Spectroscopy, Lattice dynamics, Debye temperature