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Phase separated metallic glasses were prepared in the ternary Ni-Nb-Y system by rapid quenching of the melt. For Ni-rich alloys, early stage of spinodal decomposition or an almost homogeneous glassy state is obtained due to the reduction of the critical temperature of liquid-liquid phase separation near to the glass transition temperature. In situ small-angle X-ray scattering at elevated temperature gives evidence of on-going phase separation of the glass prior to crystallisation. The structural changes during isothermal heat treatment point to a spinodal mechanism of the decomposition. For glass with low Y-content (5 at %) no indication of phase separation is found in accordance with the composition dependence of the metastable miscibility gap of the supercooled liquid. Upon heating, the phase separated glass becomes a precursor and causes the nanostructure of the Ni2Y-phase formed as the first stage of crystallization. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64

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Mesoporous silica modified with titania was prepared using the sol-gel process. The structure of these composites was studied using infrared and UV-visible spectroscopies, thermogravimetry, nitrogen sorption measurements, and scanning and transmission electronic microscopies. In light of these results, a model of formation was proposed: the material is composed of a mesoporous silica matrix and small titania particles mainly located at the surface of pore walls. The thermal stability of these composites was investigated from 650 to 1000 °C. It was shown that the increase in temperature leads to the growth of titania nanoparticles associated with the shrinkage of the mesoporous structure. Nevertheless, the whole structure remains mesoporous until 850 °C; the thermal stability is thus improved compared to pure silica or pure titania. At 1000 °C, the composites are nonporous and contain crystallized anatase titania nanoparticles with a mean diameter between 5 and 10 nm embedded in the silica matrix.