Recoil-free fractions of the 14.4 keV M$ouml$ssbauer gamma line of 57Fe in various host lattices

The recoil-free fractions in the emission of 14.4 keV Mössbauer gamma line of 57 Fe from 30 different host lattices have been determined using the black absorber technique. The force constants between the impurity-host and host-host atoms are found to be within about 20% equal for most of the hosts. For Pd the force constants between impurity-host atoms remain relatively unchanged up to 5 wt% of the impurity. In Pb, Tl and In the impurity atoms appear to diffuse into interstitial positions.