Neutron and X-Ray Small Angle Scattering (S.A.S.) Study of the Amorphous Alloy Tbsub(.25)Cusub(.75)

摘要

The magnetic properties of amorphous alloys REsub(x) Msub(x-1) (R.E.=heavy rare earths, M=Cu, Ag, Au) have been widely studied. They are of the speromagnetic type for x>=0.33 and are mictomagnetic for x<=0.33. As the magnetic order is only short range, it seemed interesting to study these alloys by small angle scattering with X-rays and neutrons. We chose alloys of Terbium and Copper for the following reasons: Tb and Cu have very different X-ray scattering amplitudes (approximately 29.65) and similar neutron scattering amplitudes (0.76x10 exp -12 cm). Also the atomic volume of Terbium (approximately 33 A exp 3 ) is almost three times that of Copper (11.8 A exp 3 ) and Cu is less absorbant than Ag or Au. Tb alloys exhibit high magnetic ordering temperatures and important moments in contrast to the majority of other alloys of the same family. One inconvenience with Terbium, however, is the large (X-ray) fluorescence (lambda Cu). In order to confirm some interpretations of S.A.S., we were obliged to determine some physical parameters such as the density and porosity and to examine the sample with microscope. These results are also given here. (Atomindex citation 12:576343)