Аннотация:Troilite (FeS) was synthesized and its Mössbauerspectra in the temperature range 90-295 K were obtained.The equilibrium isotope factors (β-factors) of iron troilitewere estimated from the temperature shift (TS) in theMössbauer spectra. The traditional estimation methodusing the Debye model to describe the 57Fe phononspectrum in troilite resulted in β-factor values for irontroilite that were significantly different from thosedetermined from nuclear inelastic resonant X-ray scatteringexperiments. Estimates of the iron β-factor for troiliteaccounting for anharmonic effects, based on both theDebye model and the Thirring expansion, showed goodagreement with the inelastic resonant X-ray scattering dataon 57Fe nuclei.