The structure factors of liquid equiatomic KSn and CsSn alloys have been determined by neutron diffraction. A distinct peak at about 1 A${\mathrm{̊}}^{\mathrm{-}1}$, the first sharp diffraction peak (FSDP), occurs in all measured structure factors. The temperature dependence of the structure has been studied for KSn: apart from the FSDP, whose position shifts toward smaller wave vector and magnitude decreases with increasing temperature, the structure factor remains essentially unaltered. The radial distribution function clearly shows three maxima in the first coordination shell. The simultaneous presence of the FSDP and several maxima in the first coordination shell are indications of formation of polyatomic species in the liquid. Application of two simple structural models, taking into account the presence of structural units, yields reasonable agreement with the measured structure factors.

• Received 26 October 1989

DOI:https://doi.org/10.1103/PhysRevB.41.5661