Structure, magnetic and magnetostrictive properties of (Tb0.7Dy0.3)0.7Pr0.3(Fe1-xCox)1.83 (0<x<0.6)

Measurements of the structure, magnetic properties, and magnetostriction were made on arc-melted polycrystalline (Tb0.7 Dy0.3)0.7Pr0.3(Fe1-xCo x)1.85 (0⩽×⩽0.6) alloys by X-ray diffraction, initial susceptibility, vibrating sample magnetometry, and standard strain gauge techniques. The measurements showed that the matrix of (Tb0.7Dy0.3)0.7Pr0.3 (Fe1-xCox)1.85 predominantly consists of the MgCu2-type cubic Laves phase, with a small amount of PuNi3-type and rare-earth rich phases. The amount of (Tb,Dy,Pr)(Fe,Co)2 in (Tb0.7Dy0.3) 0.7Pr0.3(Fe1-xCox)1.85 increases with increasing Co concentration and becomes almost the only phase present when x⩾0.4. The lattice parameter decreases approximately linearly with increasing x from 0.7357 nm when x=0 to 0.7300 nm when x=0.6. The Curie temperature increases with increasing x from 640 K when x=0 to 677 K when x=0.3, and then decreases to 572 K when x=0.6. The saturation magnetization Ms exhibits a minimum near x=0.3. The polycrystalline magnetostriction of (Tb0.7 Dy0.3)0.7Pr0.3(Fe1-xCo x)1.85 decreases monotonically with increasing x. There is no evidence of an anomalously large λ100 value as is the case for other R(Fe1-xCox)2 compounds