Neutron diffraction study of the Th(Co1-xFex)5alloys

We have studied the ordering of Fe atoms and the magnetic properties of Th(Co
1-x
Fe
x
)
5
alloys with the CaCu
5
- type structure. From the neutron diffraction analysis it is concluded that the larger Fe atoms prefer to occupy the site
3g
whereas the smaller Co prefer to occupy the site 2c. The ordering between Fe and Co in these alloys is mainly determined by stearic considerations. The Curie temperatures are found to be sensitive to the type of heat treatment. Although the bulk anisotropy of the alloys up to
x \leq 0.7
remains essentially unchanged, the coercivity decreases with increasing iron concentration. The possibility of disordered substitution of a Th atom by a pair of transition metal atoms and its role on the structural and magnetic properties is discussed.