Synthesizing pure phase Ba₃Si₆O₉N₄ by the conventional solid-state reaction method is challenging because of easily formed secondary phase Ba₃Si₆O₁₂N₂ showing similar crystal structure. In this work, an alternative low temperature synthesis method is presented, and a series of green to blue emitting (Ba, Sr)₃Si₆O₉N₄: Eu²⁺ phosphors were prepared by a mechanochemical activation route. Variations in photoluminescence properties and crystal structure, as induced by the change in phosphor composition, were investigated. Under ultraviolet-light excitation, Ba₃Si₆O₉N₄: Eu²⁺ phosphor exhibited a strong narrow green emission at 518 nm and simultaneously a weak emission at 405 nm, which are ascribed to different Eu/Ba sites in Ba₃Si₆O₉N₄ lattice proved by Density Functional Theory (DFT) calculations. A continuous green to blue emission in (Ba, Sr)₃Si₆O₉N₄: Eu²⁺ phosphors could be achieved by tuning the crystal structure and local coordination environment acting on Eu²⁺ with Sr/Ba substitution. More Sr/Ba substitution improved thermal quenching and resulted in a different characteristic of emission peak shift upon increasing the temperature.

In this paper, the unsteady cavitation phenomena on a NACA0015 hydrofoil is numerically simulated by unsteady Reynolds-Averaged Navier-Stokes (URANS) method and Large Eddy Simulation (LES) in single-fluid approaches to multiphase modelling, respectively. It is observed that the large-scale structures and characteristic periodic shedding predicted by the URANS with the modified SST k-ω turbulence model show a good qualitative match with the experimental observations but with quantitative discrepancies, such as a different cavity length and volume, and a different location of shedding. Compared to the URANS results, the LES results reproduce more details of unsteady dynamics with an improved quantitative agreement.