First X-Ray Scattering Studies on Electrostatically Levitated Metallic Liquids: Demonstrated Influence of Local Icosahedral Order on the Nucleation Barrier

Abstract

To explain the unusual stability of undercooled liquids against crystallization, Frank hypothesized that the local structures of undercooled liquids contain a significant degree of icosahedral short-range order, which is incompatible with long-range periodicity. We present here the first direct experimental demonstration of Frank's complete hypothesis, showing a correlation between the nucleation barrier and a growing icosahedral short-range order with decreasing temperature in a Ti39.5Zr39.5Ni21 liquid. A new experimental facility, BESL (Beamline Electrostatic Levitation), was developed to enable the synchrotron x-ray structural studies on deeply undercooled, reactive liquids.

Cooling rates dependence of medium-range order development inCu64.5Zr35.Zhang1, Zhang2, Wang3 et al. 2015Phys. Rev. B556310View full textAdd to dashboardCite

“…Unlike crystalline materials, MGs do not have long-range translational order. However, various experiments [3,4] and computer simulations [5,6] have revealed short-to medium-range order in MGs. Here we define the short-range order (SRO) restricted to atomic arrangement within the first coordination shell.…”

Control of organic polymorph formation: crystallization pathways in acoustically levitated droplets

“…The crystal-liquid interfacial energy arises from configurational entropy differences between crystal and liquid phases. Pronounced differences in the local structural ordering between the crystal phase and the liquid phase lead to an increased interfacial energy and consequently to a higher nucleation barrier [1,2]. Experimental and theoretical studies indicated that the CNT might not be adequate for the description of the initial nucleation process [3][4][5][6][7][8][9][10][11][12][13].…”

“…The X-ray diffraction pattern (Bruker AXS, D5000, Cu K α1 radiation) revealed that the sample consisted of the α-modification (P2 1 ). Paracetamol ( ≥ 99% purity, Sigma-Aldrich) was used without purification.…”

Reflections on symmetry and formation of axial quasicrystals

“…However, since icosahedra cannot be packed without gaps, they are distorted and/or mixed with other AETs. Furthermore, not only in solids but also in undercooled metallic melts icosahedral short-range order may not be the exception (Kelton, 2003).…”