Determination of the atomic short-range order in a Tb-Cu amorphous alloy by X-ray and neutron diffraction

X-ray ( lambda Mo ) and neutron ( lambda =0.5 and 0.7 AA) diffraction measurements were performed on an amorphous alloy (Tb 0.22 Cu 0.78 ) 0.93 H 0.04 O 0.015 Ar 0.015 . Interatomic distances and coordination numbers were determined separately from the X-ray and neutron data. These results are compared and discussed in relation to the measurement methods and data treatment. A supplementary interatomic distance obtained from the neutron measurements is discussed. The analysis of the neutron data at two wavelengths enables the authors to establish the alloy concentration, the hydrogen percentage and its effective mass. Evidence was obtained of a chemical order, whose nature is discussed.