The atomic structures in equilibrium and supercooled liquids of Zr 80 Pt 20 were determined as a function of temperature by in-situ high-energy synchrotron diffraction studies of the levitated liquids (containerless processing) using the beamline electrostatic levitation (BESL) technique. The presence of a pronounced pre-peak at q ~ 1.7 Å -1 in the static structure factor indicates medium range order (MRO) in the liquid. The position and intensity of the pre-peak remain constant with cooling, indicating that the MRO is already present in the liquid above its melting temperature. An analysis of the liquid atomic structures obtained using the Reverse Monte Carlo (RMC) method utilizing both the structure factor, S(q), from x-ray diffraction experiments and the partial pair-correlation functions from ab initio molecular dynamics (MD) simulations show that the pre-peak arises from a Pt-Pt correlation that can be indentified with icosahedral short-range order around the Pt atoms. The local atomic ordering is dominated by icosahedral-like structures, raising the nucleation barrier between the liquid and these phases, thus assisting glass formation.

No abstract

Except for a few anomalous solids and liquids, materials expand upon heating. For liquids, this should be reflected as a shift in the peak positions in the pair correlation function, g(r), to higher r. Here, we present the results of a detailed study of the volume thermal expansion coefficients and the temperature dependences of g(r) for a large number of binary, ternary, and quaternary liquids in the equilibrium and supercooled (metastable liquid below the liquidus temperature) states. The data were obtained from x-ray scattering and volume measurements on levitated liquids using the electrostatic levitation technique. Although the volumes of all liquids expand with increasing temperature, the peak positions in g(r) for the first coordination shells contract for the majority of alloy liquids studied. The second and third peaks in g(r) expand, but at rates different from those expected from the volume expansion. This behavior is explained qualitatively in terms of changes in the coordination numbers and bond-lengths as clusters in liquids break up with increasing temperature.

Erratum: Rapid chemical and topological ordering in supercooled liquid Cu 46 Zr 54 [Phys. Rev. B 83, 094116 (2011)]The constant value for the emissivity (ε), used to calculate C p (T ) [shown in Fig. 7(a)], was incorrectly stated to be ε = 0.2. The actual value used in the calculation was ε = 0.25.

Evidence for rapid ordering in a supercooled Cu 46