Liquid deposition techniques

One of the major advantages of hquid deposition techniques for the formation of SWNT networks is that they occur at room temperature this allows inclusion of heat sensitive substrates like polymers plastics and glass (7 7). A second major advantage of liquid deposition techniques is the they deconstruct network formation into two separate steps, therefore SWNT growth and deposition occurred in two separate steps. This facilitates the deposition of SWNTs onto a wide variety of substrates. Additionally, this also allows the introduction of purification and/or modification steps between SWNT growth and deposition. 

The ability to insert a step in which the SWNTs are chemically modified is another major advantage of liquid deposition techniques. Such modification is frequently necessary in order to impart selectivity for highly sensitive sensor response of SWNTs. 

Synthesis of mesoporous materials using liquid deposition techniques is shown in Fig. 3.15. This overall complex transformation can be seen simply as direct polycondensation of the inorgaific precursors around the organic micelles (or mesophase), which freezes the liquid-crystal mesostructure. 

Figure 9.1 Illustration of some liquid deposition techniques including (a) dip coating, (b) spin coating, (c) spray coating, and (d) inkjet printing.

Figure 92. Scheme of the various general steps involved in liquid deposition techniques exemplified by dip coating. 

Nowadays all over the world considerable attention is focused on development of chemical sensors for the detection of various organic compounds in solutions and gas phase. One of the possible sensor types for organic compounds in solutions detection is optochemotronic sensor - device of liquid-phase optoelectronics that utilize effect of electrogenerated chemiluminescence. In order to enhance selectivity and broaden the range of detected substances the modification of working electrode of optochemotronic cell with organic films is used. Composition and deposition technique of modifying films considerably influence on electrochemical and physical processes in the sensor. 

Hurst, K.M., Roberts, C. and Ashurst, W. (2009) A gas-expanded liquid nanoparticle deposition technique for reducing the adhesion of silicon microstructures. Nanotechnology, 20 (18), 185303. 

Both wet-ceramic techniques and direct-deposition techniques require preparation of the feedstock, which can consist of dry powders, suspensions of powders in liquid, or solution precursors for the desired phases, such as nitrates of the cations from which the oxides are formed. Section 6.1.3 presented some processing methods utilized to prepare the powder precursors for use in SOFC fabrication. The component fabrication methods are presented here. An overview of the major wet-ceramic and direct-deposition techniques utilized to deposit the thinner fuel cell components onto the thicker structural support layer are presented below. 

As we discussed earlier for the solid-liquid separation technique, filtration separates particles by forcing the fluid through a filtering medium on which solids are deposited. The conventional filtration involves the separation of large particles (dp > 10 pm) by using canvas, synthetic fabrics, or glass fiber as filter medium. 

M/SC nanoparticles in size from 1 to 10 nm are of greatest interest because their electronic structure depends markedly on the particle size [4-6]. There are now a lot of methods for a deposition of M/SC and dielectric on solid substrates from liquid or gaseous phase to produce composite films containing M/SC nanoparticles inside or on a surface of a dielectric matrix. Liquid-phase technique uses colloidal solutions of M/SC nanoparticles. Such solutions are formed by chemical reactions of various precursors in the presence of stabilizers, which are adsorbed on the surface of nanoparticles and preclude their aggregation. But it is necessary to take into account, that... 

The synthesis of large clusters such as [A Ris]3- (Chapters 2 and 3) proceeds by A1 atom cluster-core build up. Cluster-core growth is terminated at some point by external ligands. The method of Schnockel is a variation of metal-atom vapor-deposition techniques and relies on (a) the reversibility of the equilibrium between the liquid metal, e.g., Al, and gaseous metal halide, e.g., AICI3, with gaseous subhalide, e.g., A1C1 (b) the shift in equilibrium position with temperature and (c) competitive rates at similar temperatures of subhalide disproportionation to metal... 

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