Mesoporous silica films work as templates to form uniform nanoparticles of Au and Pt. The composite materials form an array of metal nanoparticles (diameter ca. 2.5 nm) in the one-dimensional mesopores (pore diameter 2.7 nm), showing an ordered structure in the TEM observation. The nanoparticles are isolated from the silica film by dissolving with a diluted HF solution, and in the presence of 1-dodecanethiol unsupported Au nanoparticles form a superlattice structure.

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Transparent Tb 3+ and Yb 3+ codoped oxyfluoride glass ceramics containing CaF 2 nanocrystals were prepared by melt quenching and subsequent heat treatment. Crystallization kinetics of CaF 2 nanocrystals was investigated by differential scanning calorimetric method. The average apparent activation energy E a of the crystallization was ϳ498 kJ/ mol. Moreover, the value of the Avrami exponent n was 1.01. These results suggest that the crystallization mechanism of CaF 2 is a diffusion controlled growth process of needles and plates of finite long dimensions. X-ray diffraction patterns and transmission electron microscopy image confirmed the CaF 2 nanocrystals in the glass ceramic. Ultraviolet ͑UV͒ and visible emission spectra of the as-made glass and the glass ceramic with an excitation of a 974 nm laser diode were recorded at room temperature. An intense UV emission at 381 nm was observed in the glass ceramic. The origin of the enhancement of the emission at 381 nm was investigated using spectroscopic technique and Judd-Ofelt analysis. The enhancement of the emission at 381 nm could be attributed to the change of the ligand field of Tb 3+ ions due to the incorporation of some Tb 3+ and Yb 3+ ions into CaF 2 nanocrystals in the glass ceramic.

The synthesis of nanometer-sized materials has attracted much attention because of the unique catalytic, magnetic, optical, and electronic properties of such materials. Since the physicochemical properties of nanomaterials are highly dependent on their size, shape, and arrangement, techniques for controlling the nanostructure and organization of materials are highly desirable. Ordered mesoporous materials are potential candidates for fabricating nanomaterials because of their uniform nanopores of various sizes (1.5-30 nm), shapes (cylindrical and cagelike), and arrangements (2D and 3D hexagonal, cubic Pm3 n, cubic Ia3 d, etc). [1][2][3] To date, nanoparticles or nanowires of Pt, [4] Ag, [4d,5] Pd, [4e,6] and Au, [4d,e] using mesoporous powders or thin films. In most cases, the pores were partially filled with materials, and nanoparticles or rods were randomly distributed in mesoporous-silica matrices. Recently, the syntheses of ordered nanoparticle arrays of CdS, [9] Au, [10] and Pt [10] in mesoporous silica films have been reported by independent groups. Fan et al. reported the synthesis of gold nanocrystal/silica mesostructured thin films with a cubic symmetry (Fm3m) via self-assembly of water-soluble nanocrystal micelles with soluble silica.[11] These periodic nanodot arrays in silica thin films could be applied to singleelectron devices mediated by coupling interactions with neighboring nanodots. The ordered lattice and the perfect packing of dots are very important for the 3D array of multitunnel junctions, and it should be possible to control the properties of single-electron devices by changing the pore size and arrangement of the mesoporous silica thin film.Here we present the synthesis of a highly ordered Pt nanodot array of cubic symmetry simply by immersing a mesoporous silica thin film into a Pt-precursor solution followed by photoreduction. Two types of cages of mesoporous thin films have been fully filled with Pt nanoparticles of approximately 4 nm diameter, and an exceptionally ordered cubic-lattice array of nanodots has been obtained.The mesoporous thin films and the Pt-filled mesoporous thin films on silicon wafers were scratched off and placed on Cu grids for high-resolution transmission electron microscopy (HRTEM) measurements. The HRTEM images of both the mesoporous thin films and the Pt-filled thin films are displayed in Figure 1. (Large-area HRTEM images are shown in the Figs. S1 and 2 in the Supporting Information).