A Comparative Mössbauer Spectral Study of the Electronic and Magnetic Properties of Nd₆Fe₁₃Ag and Nd₆Fe₁₃AgH₁₃

The Mössbauer spectra of Nd6Fe13Ag and Nd6Fe13AgH13 have been measured between 85 and 295 K and analyzed with a model that takes into account the basal magnetic anisotropy, the iron and hydrogen near-neighbor environments of the five crystallographically and magnetically inequivalent 4d, 16k, 16k\u27, 16l1, and 16l2 iron sites in the former and the six crystallographically and magnetically inequivalent 4d, 16k, 16k\u27, 16l1, 16l2-1 and 16l2-2 iron sites in the latter, where the additional site results from a predominance of hydrogen as near-neighbors on the iron 16l2 site. The increases in hyperfine field and isomer shift observed upon hydrogenation are in agreement with the increase in Wigner-Seitz cell volumes of each site and the changes in the near-neighbor environments