Thin films template synthesis

Kim YT, Han JH, Hong BH, Kwon YU (2010) Electroehemieal synthesis of CdSe quantum-dot arrays on a graphene basal plane using mesoporous silica thin-film templates. Adv Mater 22 515... 

Similarly, monometallic Rh, Pd, and Au and bimetallic Pt-Rh and Pt-Pd nanowires were prepared in FSM-16 or HMM-1 by the photoreduction method [30,33,34]. The bimetallic wires gave lattice fringes in the HRTEM images, and the EDX analysis indicated the homogeneous composition of the two metals. These results show that the wires are alloys of Pt-Rh and Pt-Pd. Mesoporous silica films were also used as a template for the synthesis of uniform metal particles and wires in the channels [35,36]. Recently, highly ordered Pt nanodot arrays were synthesized in a mesoporous silica thin film with cubic symmetry by the photoreduction method [37]. The... 

Recent developments in zeolite synthesis and new materials include (i) the use of combinatorial methodologies, microwave heating, multiple templates or SDAs and concentrated fluoride media in synthesis, (ii) synthesis using the charge density mismatch (COM) concept, (iii) synthesis in ionothermal media, (iv) synthesis with complex designer templates or SDAs, (v) synthesis of nanozeohtes, (vi) zeoUte membranes and thin films (vii) and germanosilicate zeoHtes [76]. Several of these developments are discussed here. 

Both the molecular template and the self-assembly techniques presented above have limited control over the final shape of the solid, since this is generally obtained in the form of a powder, fibers, or thin films. It is possible, however, to control the shape and size of solids by combining the former techniques with techniques that restrict the volume in which the synthesis takes place. The final goal is to have control over the solids at the molecular as well as macroscopic level, in order to have in a single material properties emerging from several levels of scale. Such structures are referred to as hierarchical [2, 6]. 

Rare earth silicates exhibit potential applications as stable luminescent materials for phosphors, scintillators, and detectors. Silica and silicon substrates are frequently used for thin films fabrication, and their nanostructures including monodisperse sphere, NWs are also reliable templates and substrates. However, the composition, structure, and phase of rare earth silicates are rather complex, for example, there are many phases like silicate R2SiOs, disilicate R2Si207 (A-type, tetragonal), hexagonal Rx(Si04)602 oxyapatite, etc. The controlled synthesis of single-phase rare earth silicate nanomateriais can only be reached with precisely controlled experimental conditions. A number of heat treatment based routes, such as solid state reaction of rare earth oxides with silica/silicon substrate, sol-gel methods, and combustion method, as well as physical routes like pulsed laser ablation, have been applied to prepare various rare earth silicate powders and films. The optical properties of rare earth silicate nanocrystalline films and powders have been studied. 

The dominant class of pearl luster pigments is based on platelets of natural mica coated with thin films of transparent metal oxides [5.122-5.125, 5.127-5.130, 5.137]. The mica substrate acts as a template for the synthesis and as a mechanical support for the deposited thin optical layers of the pearl luster pigments. Mica minerals are sheet layer silicates. Pearl luster pigments are usually based on transparent muscovite mica only some are based on synthetic phlogopite. Although muscovite occurs worldwide, few deposits are suitable for pigments. Natural mica is biologically inert and approved for use as a filler and colorant. 

We were interested in the potential of the syndiesized diblock copolymers as templates in the synthesis of mesostructured silicate materials. Our focus was the pr aration of mesoordered thin films via the evaporation-induced self-assembly process [7]. For this purpose PDMS-b-PEO were mixed with a precursor solution containing the network-building species, and films were produced via a dip-coating procedure [8]. XRD diffraction patterns confirmed the formation of lamellar materials which were stable upon calcination at 430 °C/3 h. 

Porous materials can also be coated with zeolite films by direct synthesis. For example, microcellular SiOC ceramic foams in the form of monoliths were coated on their cell walls with thin films of silicalite-1 and ZSM-5 using a concentrated precursor solution for in situ hydrothermal growth (Fig. 9).[62] The zeolite-coated monoliths show a bimodal pore system and are thermally stable to at least 600 °C. A related strategy is based on the conversion of macroporous Vycor borosilicate glass beads, having pores of about 100 nm, to MFI-type zeolite-containing beads retaining the same macroscopic shape.[63] This conversion was achieved by hydrothermal treatment with an aluminium source and a template such as TPABr. 

In the synthesis of mesostructured thin films, modification or functionalization of the material can also be achieved by varying the template molecule. 

One-dimensional (1-D) nanosbuctures (b) are composed mainly of nanowires, nanorods and nanobelts. Spontaneous growth, template-based synthesis and electrospinning are considered bottom-up approaches, while lithography is a top-down technique [7, 84]. Two-dimensional (2-D) nanostructures (c) involve thin films, which have been the object of intensive study for almost a century and for which many methods have been developed and improved. 

In the case of soft-template self-assembly synthesis, mesostructure assembly and morphology growth can be controlled concurrently. Due to the versatility of the solvent-based soft-template self-assembly process, highly ordered mesoporous carbons can be produced relatively easily with different morphologies such as thin film and membrane, " monolith,fibre,sphere, rod, single-crystal, " and discus-like crystal. Initially, mesoporous carbons synthesised with soft templates were exclusively in the form of films. " ... 

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