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A volume-averaged model for finite-rate diffusion of hydrogen in the melt is developed to predict pore formation during the solidification of aluminum alloys. The calculation of the micro-/macro-scale gas species transport in the melt is coupled with a model for the feeding flow and pressure field. The rate of pore growth is shown to be proportional to the local level of gas supersaturation in the melt, as well as various microstructural parameters. Parametric studies of one-dimensional solidification under an imposed temperature gradient and cooling rate illustrate that the model captures important phenomena observed in porosity formation in aluminum alloys. The transition from gas to shrinkage dominated porosity and the effects of different solubilities of hydrogen in the eutectic solid, capillary pressures at pore nucleation, and pore number densities are investigated in detail. Comparisons between predicted porosity percentages and previous experimental measurements show good correspondence, although some uncertainties remain regarding the extent of impingement of solid on the pores.

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Nontrivial topological surface states (TSSs), which possess extraordinary carrier mobility and are protected by the bulk symmetry, have emerged as an innovative platform to search for efficient electrocatalysts toward hydrogen evolution reaction (HER). Here, a Sn-based nontrivial metal Ru 3 Sn 7 is prepared using electrical arc melting method. The results indicate that the (001) crystal family of Ru 3 Sn 7 possesses nontrivial TSSs with linear dispersion relation and large nontrivial energy window. Experimental and theoretical results demonstrate that nontrivial TSSs of Ru 3 Sn 7 can significantly boost charge transfer kinetics and optimize adsorption of hydrogen intermediates due to bulk symmetry-protected band structures. As expected, nontrivial Ru 3 Sn 7 exhibits superior HER activity to Ru, Pt/C, and trivial counterparts (e.g., Ru 2 Sn 3 , IrSn 2 , and Rh 3 Sn 2 ) with higher ratios of noble metals. Furthermore, the wide pH-range activity of topologically nontrivial Ru 3 Sn 7 implies the robustness of its TSSs against pH variation during the HER. These findings provide a promising approach to the rational design of topologically nontrivial metals as highly efficient electrocatalysts.

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The improvement of high‐performance narrow‐band green phosphors in backlight display applications is still a major challenge. Based on the UCr4C4 type of oxide phosphor, the high‐performance narrow‐band green phosphors Rb3M(Li3SiO4)4:Eu2+ (M = Rb or Na) are studied in different luminous positions. Benefiting from the replacement of Rb by Na, the change of the local environment in the crystal structure of Rb3Na(Li3SiO4)4:Eu2+ (R3NLSO:Eu2+) leads to the decrease of Stokes shift, which improves the quantum efficiency. Moreover, change in the local environment enhances the structural rigidity, which makes the thermal and chemical stability better. The R3NLSO:8%Eu2+ phosphor presents a narrow‐band green emission centered at 527 nm, excellent thermal stability (102% @150 °C of the integrated emission intensity at room temperature), and high internal/external quantum efficiency (85.3%/40.4%). The white light‐emitting diode (wLED) using R3NLSO:8%Eu2+ phosphor presents a superior luminous efficiency of 128.3 lm W‐1 and a wide color gamut. All the results indicate that R3NLSO:8%Eu2+ green phosphor has great application prospects in the field of liquid crystal display. This work also provides important guiding significance for the optimization of alkali metal element type of phosphors.