Transparent crystalline yttrium aluminum garnet (YAG; Y3Al5O12) is a dominant host material used in phosphors, scintillators, and solid state lasers. However, YAG single crystals and transparent ceramics face several technological limitations including complex, time-consuming, and costly synthetic approaches. Here we report facile elaboration of transparent YAG-based ceramics by pressureless nano-crystallization of Y2O3–Al2O3 bulk glasses. The resulting ceramics present a nanostructuration composed of YAG nanocrystals (77 wt%) separated by small Al2O3 crystalline domains (23 wt%). The hardness of these YAG-Al2O3 nanoceramics is 10% higher than that of YAG single crystals. When doped by Ce3+, the YAG-Al2O3 ceramics show a 87.5% quantum efficiency. The combination of these mechanical and optical properties, coupled with their simple, economical, and innovative preparation method, could drive the development of technologically relevant materials with potential applications in wide optical fields such as scintillators, lenses, gem stones, and phosphor converters in high-power white-light LED and laser diode.

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Diverse supports (ZSM-5, SBA-15, MCM-41, Al2O3 and SiO2) with various mesoporous structures were introduced to fabricate nickel-based catalysts for the CO2 methanation by incipient wetness impregnation method. Ni/ZSM-5 catalyst displayed the most active catalytic properties, followed with Ni/SBA-15, Ni/Al2O3, Ni/SiO2 and Ni/MCM-41 catalysts. The excellent catalytic property of Ni/ZSM-5 catalyst was resulted from the basic property and the synergistic effect between nickel metal and support. The reactivity of the reaction intermediate monodentate formate in Ni/ZSM-5 catalyst was more active than that of bidentate formate species as identified by in situ infrared spectroscopy. The Ni/ZSM-5 catalyst performed with excellent stability and no deactivation up to 100 h. XRD, BET and TGA/DTA characterization further indicated that Ni/ZSM-5 catalyst had excellent resistance to carbon deposition and metal sintering. What is more, the kinetics of CO2 methanation over Ni/ZSM-5 catalyst was also studied.