X-ray-absorption fine-structure measurements at the Sn and Sb K edges were made on ${\mathrm{Nb}}_3$Sn, ${\mathrm{Nb}}_3$Sb, and ${\mathrm{Nb}}_3$${\mathrm{Sn}}_{1\mathrm{-}\mathrm{x}}$${\mathrm{Sb}}_{\mathrm{x}}$ alloys. No temperature-dependent anomalies were noted for the Sn-Nb and Sb-Nb distances or for the broadening in these distances for temperatures from 4.2 K to well above the transition temperatures. The temperature dependence of the broadenings fits an Einstein oscillator model well, with Einstein temperatures of 237 K for ${\mathrm{Nb}}_3$Sn and 254 K for ${\mathrm{Nb}}_3$Sb. These results also agree with recent theoretical calculations. The Debye-Waller–type broadening in the Sn-Nb and Sb-Nb distances for the alloys are not equal to one another, but instead are nearly equal to those of the binary end-point compounds, i.e., to ${\mathrm{Nb}}_3$Sn and ${\mathrm{Nb}}_3$Sb, respectively.

• Received 6 July 1987

DOI:https://doi.org/10.1103/PhysRevB.37.54