X-ray diffraction experiments and ab initio molecular dynamics (AIMD) simulations have been performed to investigate the atomic structure of liquid silicon into the deeply supercooled region. The levitation technique used has made it possible to extend the measurements down to a temperature of 1458 K, 230 K below the equilibrium melting point. The x-ray and AIMD results, which are in reasonable agreement, show conclusively that the tetrahedral order is reinforced and that the coordination number decreases as the liquid is supercooled, with implications for the liquid–liquid phase transition.

Collective excitations have been observed in liquid aluminum oxide at high temperatures by combining a containerless sample environment with inelastic x-ray scattering. The excitation spectra show a well-defined triplet peak structure at lower wave vectors Q (1 to 6 nanometers-1) and a single quasi-elastic peak at higher Q. The high-Q spectra are well described by kinetic theory. The low-Q spectra require a frequency-dependent viscosity and provide previously unknown experimental constraints on the behavior of liquids at the interface between atomistic and continuum theory.

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are analyzed as a function of their structure. The influences of cation size and electronegativity are discussed in relation with the Struck and Fonger theory, with a view to developing one or more of those compounds as phosphors in relation with the development of white LEDs. It appears that there are various excited states implied in the absorption process, with partially radiative transfer between them. All the radiative mechanisms are strongly related to temperature. Due to their electronegativity, tungstate compounds are the most promising, compared to molybdate ones, especially those in the monoclinic P 2/n structure.

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