Magnetic and crystallographic properties of substituted Ce2Co17−xTx compounds (T = Ti, V, Cr, Mn, Fe, Cu, Zr, and Hf)

Abstract

The ternary Ce2Co17-based systems in which Co is replaced by Ti, V, Cr, Mn, Fe, Cu, Zr, and Hf have been studied to ascertain the effect of substitution on their magnetic and crystallographic properties. X-ray diffraction experiments indicate that Mn and Fe stabilize the rhombohedral Th2Zn17 structure, while Ti, V, Cr, Cu, Zr, and Hf stabilize the hexagonal Th2Ni17 structure. The unit cell volume is found to increase by introducing substituents for all the systems. The Curie temperatures TC decrease monotonically with increasing x, in the order Fe<Hf<Cu<Zr<Ti<Mn<Cr<V. The saturation magnetizations Ms increase with increasing x for the Fe system with x?10 and the Mn system with x<2. It is found that Ms decreases sharply with x in the Mn system with x?2 and in the other systems, the magnitude of the effect being in the order Hf≳V≳Cr≳Mn≳Zr≳Ti≳Cu. The rate of decrease is larger than that expected as a simple dilution except for the Cu system. The anisotropy field HA shows a maximum around x = 2 for the Cr, Mn, and Fe systems, indicating that T atoms substitute preferentially for the dumbbell cobalts in Ce2Co17−xTx with x?2. The magnitude of the effect of substitution on HA is found to be in the order Zr≳V≳Hf≳Ti≳Cr≳Mn≳Fe≳Cu in the range of x?1.0. Crystallographic and magnetic characteristics suggest that all substituents replace Co when the ternaries are formed.