Anomalous behaviour of the Debye temperature in Fe-rich Fe–Cr alloys

Debye temperature, ΘD, of Fe-rich Fe100−xCrx disordered alloys with 0 ≤ x ≤ 30 was determined from the temperature dependence of the centre shift of Mössbauer spectra recorded in the temperature range of 60–300 K. Its compositional dependence shows a non-monotonous behaviour with two maxima: a sharp maximum at x ≈ 3 having a relative increase of ∼12% compared to a pure iron, and a broad one centred at x ≈ 15 with a relative height of ∼10%. The maxima coincide well with those found or calculated for various physical properties like the spin-waves stiffness coefficient, Do, the magnetic moment per Fe atom and the Curie temperature, suggesting a magnetic origin as a possible source of the anomalous behaviour of ΘD observed in this study.