Mössbauer Effect in Dy161 in Metallic Dysprosium, DyFe2, and DyAl2

Abstract

The recoilless absorption spectra of the 26-keV $\gamma$ rays from ${\mathrm{Dy}}^{161m}$ in ${\mathrm{Dy}}^{161}$ situated in Dy metal, Dy${\mathrm{Fe}}_2$, and Dy${\mathrm{Al}}_2$ were measured at various temperatures. A value of (-825±30) Mc/sec was found for the magnetic hyperfine constant ($g_0{\mu }_n{H}_{\mathrm{eff}}$) of the ground state of ${\mathrm{Dy}}^{161}$ in Dy metal at 20°K. This value is in very good agreement with the "free-ion" value calculated for the ${\mathrm{Dy}}^{3+}$ ions in the fully magnetized state ($J_z=J$) from data on electron spin resonance in dilute salts. The internal magnetic field acting on the Dy nucleus in Dy${\mathrm{Fe}}_2$ at magnetic saturation is (14±2)% higher than in Dy metal. The magnetic field acting in Dy${\mathrm{Al}}_2$ at magnetic saturation is the same, within the experimental errors, as in Dy metal. The ratio of the magnetic moments of the 26-keV level and the ground state of ${\mathrm{Dy}}^{161}$ was found to be -1.19±0.05. An isomeric shift of (2.5±0.4) mm/sec was found between Dy metal and ${\mathrm{Dy}}_2$ ${\mathrm{O}}_3$ absorbers. The isomeric shifts of Dy${\mathrm{Al}}_2$ and Dy${\mathrm{Fe}}_2$ absorbers relative to a ${\mathrm{Dy}}_2$ ${\mathrm{O}}_3$ absorber were found to be (0.4±0.4) mm/sec.