Crystallographic data and magnetic properties of RT6Ge6 compounds (R Sc, Y, Nd, Sm, GdLu; TMn, Fe)

Activation Energies of Crystallization in Amorphous RMn4.5Ge4.5Fe1.5Al1.5(R = La, Y, Dy) Alloys

“…DyMn 4.5 Ge 4.5 Fe 1.5 Al 1.5 ( Fig. 3) crystallizes in orthorhombic TbFe 6 Sn 6 -type structure with Cmcm (number 63) space group as already found earlier [4]. Also amorphous YMn 4.5 Ge 4.5 Fe 1.5 Al 1.5 alloy crystallizes in the same structure.…”

“…Full substitution of Mn and Ge by Fe and Al leads to the creation of the second parent compound. DyFe 6 Al 6 has a disordered CeMn 4 Al 8 -type structure with I4/mmm space group [4]. However, the RMn 6−x Ge 6 with light rare earths or La crystallize in the YCo 6 Ge 6 structure belonging to the hexagonal P 6/mmm space group [4,6,7].…”

“…DyMn 6 Ge 6 crystallizes in the hexagonal HfGe 6 Fe 6 -type structure (P 6/mmm) [4,5]. Full substitution of Mn and Ge by Fe and Al leads to the creation of the second parent compound.…”

“…DyFe 6 Al 6 has a disordered CeMn 4 Al 8 -type structure with I4/mmm space group [4]. However, the RMn 6−x Ge 6 with light rare earths or La crystallize in the YCo 6 Ge 6 structure belonging to the hexagonal P 6/mmm space group [4,6,7]. On the other hand, the tetragonal compounds RFe 6 Al 6 only form for the heavy rare earths, for Y and U and do not form for La and the light rare earths [8].…”

Symmetry and magnetic structures

“…Experimentally, the refinement of the phase factor between the two orbits constraining the amplitudes to be the same (two free parameters) gives = 0.015 (6) The compound DyMn 6 Ge 6 crystallizes in the well known HfFe 6 Ge 6 structure [37]: space group P 6/mmm, unit cell parameters a ≈ 5.21 Å, c ≈ 8.15 Å. All the compounds RMn 6 Ge 6 (R: rare earth) have a macroscopic ferrimagnetic behaviour, however their magnetic structures are quite complex and vary with temperature.…”