Crystallographic ordering and magnetic structure in the next-to-ternary RCo_(1-x)Ni_x compounds (R = Gd-Lu)

摘要

The equiatomic RT phases (R = rare earth, T = Co, Ni) are formed only by Ni and not with Co; the compounds containing light lanthanides and Gd crystallize in the orthorhombic CrB-type, while those formed by heavier R adopt the orthorhombic FeB-type structures1. The solubility of Co in the CrB-type GdNi intermetallic has been previously reported to reach about 20 at.%2,3. On the other hand, for some of the heavy R, earlier literature data reported the existence of a ternary R5Co_3Ni_2 phase adopting the MoB-type4. During our previous work on the Gd_3Ni_2-to-Gd_3CoNi solid solution system5, we also faced with a new phase GdCo_(1-x)Ni_x, no longer crystallizing in the CrB-type but in a tetragonal cell of the MoB-type or, most likely, a derivative of this prototype. Therefore, we have investigated the formation, crystal structure and physical properties of the RCo_(1-x)Ni_x compounds (with R = Gd and some of the heavy R) in view of their potential for a strong magnetocaloric effect.