Structural and magnetic properties of (NdxR1-x)3Fe24Cr5 (R=Gd and Tb) intermetallic compounds

The crystal structure and magnetic properties of (NdxR1-x)3Fe24Cr5 (R=Gd and Tb) compounds with x=0.0-0.8 have been investigated by means of X-ray diffraction and magnetic measurements. All the samples are single phase and crystallize in the Nd3(Fe,Ti)29-type structure with space group A2/m. As the Nd content increases, the lattice parameters a, b, c and the unit-cell volume V increase in both the (NdxGd1-x)3Fe24Cr5 and the (NdxTb1-x)3Fe24Cr5 compounds due to the lanthanide contraction. The room-temperature easy magnetization direction changes to the [040] direction with increasing Nd content. The Curie temperature of (NdxGd1-x)3Fe24Cr5 decreases monotonically upon substitution of Nd for Gd, while the Curie temperature of the (NdxTb1-x)3Fe24Cr5 compounds decreases with the Nd content for x=0-0.4 and increases for x=0.4-0.8. The saturation magnetization MS increases monotonically with increasing Nd content for both compound systems and can be described in terms of a simple dilution model