Evolution of the Peierls distortion in liquid As xSb 1-x compounds

The local order in the liquid binary alloy As xSb 1-x (0lesxles1) is studied by short-wavelength (lambda=0.7 Aring) neutron scattering. The coordination number (Z) and the interatomic distances (d) are analyzed in terms of the As concentration: Z increases continuously, from a value of 3.5 for pure arsenic to a value of 6.3 for pure antimony, whereas d shows a departure from Vegard's rule. The interatomic distance increases in the range 0.15lesxles1.00 and is almost constant in the range 0.00lesxles0.15. A simple tight-binding model is developed, which indicates that the relevant parameter is the hardness of the core repulsion between the atoms