Hydrogenation effects on the magnetic and crystal-field interactions in theR2Fe14BHx(R=Gd,Pr,Dy)compounds

摘要: The magnetic properties of the ${R}_{2}{\mathrm{Fe}}_{14}{\mathrm{BH}}_{x}$ $(R=\mathrm{Gd},\mathrm{Pr},$ and Dy) compounds have been studied by measuring low-field ac susceptibility vs temperature magnetization applied field on magnetically aligned samples. A strong reduction in magnetocrystalline anisotropy Gd-based is observed, remain axial measured range. hydrogen induced spin reorientation transition (HISRT) takes place ${\mathrm{Dy}}_{2}{\mathrm{Fe}}_{14}{\mathrm{BH}}_{x}$ series for $xg~1,$ with ${T}_{s}$ increasing content. In ${\mathrm{Pr}}_{2}{\mathrm{Fe}}_{14}{\mathrm{BH}}_{x}$ no HISRT found, however $0lxl~3$ we observe first-order processes (FOMP), critical ${H}_{c}$ decreasing For ${\mathrm{Pr}}_{2}{\mathrm{Fe}}_{14}{\mathrm{BH}}_{5.5}$ compound so that ${H}_{c}\ensuremath{\approx}0,$ remains a conical phase range (5 -- 470 K). We combined analytical methods crystalline electric field-mean model to obtain quantitative evaluation effect hydrogenation crystal-field interactions. found observed behavior Gd, Dy, Pr can be explained decrease Fe sublattice (in Dy series) parameters ${B}_{n0}$ $(n=2,$ 4, 6) under hydrogenation. variations R-Fe exchange interaction seem minor influence behavior.