Mean-Square Displacement Measurements ofFe57in Zn

The Mössbauer effect of ${\mathrm{Fe}}^{57}$ in polycrystalline Zn has been measured as a function of temperature. It was round that the quadrupole splitting between 120° and 373°K decreases from 0.50±0.01 to 0.46±0.01 mm/sec. The chemical shift with respect to an Fe absorber at room temperature is -0.525±0.010 mm/sec. From intensity measurements of the two quadrupole lines, the mean-square displacement $〈x^2〉$ can be evaluated. At room temperature $〈x^2〉$ parallel to the $c$ axis was found to be ${〈x^2〉}_{\mathrm{II}}=0.0231\mathrm{}\pm 0.0016$ ${\mathrm{\AA }}^2$ and the anisotropy of the mean-square displacement $\epsilon =\frac{{〈x^2〉}_{\perp }}{{〈x^2〉}_{\mathrm{II}}}$ is found to be $\epsilon =0.33\mathrm{}\pm 0.05$. The results are compared with lattice-dynamical calculations.