Test for the influence of relaxation on Mössbauer spectra of (Fe0.65Ni0.35 1−x Mn x alloys by the sharpening method

A mathematical procedure which gives an opportunity to distinguish between relaxation and static mechanisms of the Mössbauer line broadening is developed. It is based on the method of Mössbauer line sharpening developed recently and allows one to answer unambiguously the question whether or not relaxation manifests itself in Mössbauer measurements by examinign the wings of the spectrum. The procedure was applied to the spectra of (Fe_0.65Ni_0.35)_1–x Mn _x alloys withx=0 (INVAR) andx=0.047, where the mechanism of the line broadening has not been clarified so far. An analysis of the spectra shows that in the temperature range 4 to 300 K no relaxation is observed and the line broadening is mainly caused by the distributions of magnetic hyperfine fields.