Mössbauer effect studies of RFe11Ti and RFe11TiH (R=Y,Gd, Er)

The Mössbauer spectra of ferromagnetic RFe₁₁Ti and RFe₁₁TiH_x   (R=Y$R=\mathrm{Y}$, Gd, Er, x=0$x=0$, 1) have been investigated in the temperature range 20–300 K and analysed in terms of a new model which allows a better fit of the spectra using less constraints than previously reported analyses. In addition to the dependence of magnetic hyperfine field and isomer shift on the number of Ti nearest-neighbours (NN) of the Fe atoms, this new model also considers the effect of the average interatomic distances between Fe atoms on the 8i, 8f and 8j crystallographic sites. Magnetic hyperfine fields were found to decrease with the average interatomic distances for Fe atoms on the same sites and with the same number of iron NN. This decrease was however lower than that due to the presence of one additional titanium NN. Furthermore the present model distinguishes the 8f from the 8j sites on the basis of the relative areas of the corresponding sextets. It leads to higher average magnetic hyperfine fields and isomer shifts for the 8f site as compared to the 8j sites which may be understood on the basis of electronic charge transfer between the rare-earth and Fe atoms. The dependence of hyperfine parameters on the number of titanium NN and on hydrogenation is similar to those previously reported.