Thick nanocrystalline

Palladium and gold Palladium electrodeposition is of special interest for catalysis and for nanotechnology. It has been reported [49] that it can be deposited from basic chloroaluminate liquids, while in the acidic regime the low solubility of PdCl2 and passivation phenomena complicate the deposition. In our experience, however, thick Pd layers are difficult to obtain from basic chloroaluminates. With different melt compositions and special electrochemical techniques at temperatures up to 100 °C we succeeded in depositing mirror-bright and thick nanocrystalline palladium coatings [10]. 

Figure 6.19 Photocurrent as a function of time for a 10.0 mm thick nanocrystalline Ti02 electrode modified with [Ru(dcbpy)2(NCS)2], where the electrolyte is propylene carbonate containing 0.1 M KI with different concentrations of lithium trifluoromethanesulfonate (a) 0.1 M (b) 0.05 M (c) 0.025 M (d) 0 M. Reprinted with permission from A. Solbrand, A. Henningson, S. Sodergren, H. Lindstrom, A. Hagfeldt and S.-E. Lindquist, /. Phys. Chem., B, 103,1078 (1999). Copyright (1999) American Chemical Society...

Fig. 4 Photocurrent action spectra (IPCE) obtained for solid Ti02/spiro-OMeTAD heterojunctions, sensitized with three different sensitizers. (For device structure, see Fig. 3.) The dyes were absorbed from above solution for 48 hours at room temperature. All devices are based on 4-pm thick nanocrystalline TiOz electrodes and spiro-OMeTAD as hole conducting layer (0.070 mol% spiro-OMeTAD++(PFe) in respect to spiro-OMeTAD the spin coating solution contained 15 mM Li[(CF3S02)2N]). The counter electrode was a 10-nm thick gold layer.

Surfactant templating chemistry can be extended to many nonsilicate compositions after modifications to the synthesis route. These materials are less structurally stable than the mesoporous silicates, which is attributed to the thinness of the amorphous pore walls ( 1 to 2 nm). Stucky and coworkers [85,86] showed that this problem could be mitigated by preparing the materials with thicker walls. To prepare mesoporous WO3, they dissolved a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer and WCle salt in ethanol, and dried the resulting solution in open air. The tungsten salt reacted with moisture to undergo hydrolysis and condensation reactions. These chemical reactions caused the eventual formation of amorphous WO3 around triblock copolymer micelle-like domains, and after calcination at 400 C, a mesoporous WO3 with thick, nanocrystalline walls ( 5 nm) and surface area of 125 m /g was formed. 

Recently Butler et al. [4] reported the deposition of nanocrystalline diamond films with the conventional deposition conditions for micrometer-size polycrystalline diamond films. The substrate pretreatment by the deposition of a thin H-terminated a-C film, followed by the seeding of nanodiamond powder, increased the nucleation densities to more than 10 /cm on a Si substrate. The resultant films were grown to thicknesses ranging from 100 nm to 5 fim, and the thermal conductivity ranged from 2.5 to 12 W/cm K. 

The sensitive layers that have been used throughout this book consist of nanocrystalline tin-oxide thick films. The resistance change is the result of a multitude of reactions taking place at the surface and in the bulk. This resistance change depends also on the morphology of the sensitive layer and the contact-electrode geometry. Due... 

Deposition and patterning of the bottom magnetic pole follow. The pole is usually electroplated with a through-photoresist window frame mask to a thickness level of 2 to 4 fim. Note that whereas the magnetic pole is made into a pancake shape to increase the head efficiency, it is the narrow p>ole tip s dimension that determines the narrow track width. As stated, the widely used Co-based alloy magnetic poles are elec-trodeposited (wet process). Nanocrystalline FeN-based alloys are sputter-deposited in a vacuum chamber (dry process). 

Nanocrystalline semiconductor thin film photoanodes, commonly comprised of a three dimensional network of inter-connected nanoparticles, are an active area of photoelectrochemistiy research [78-82] demonstrating novel optical and electrical properties compared with that of a bulk, thick or thin film semiconductor [79,80]. In a thin film semiconductor electrode a space charge layer (depletion layer) forms at the semiconductor-electrolyte interface charge carrier separation occurs as a result of the internal electric... 

This special nanocrystalline material may be further considered in the manner of a layered magnetic flux path material, wherein (a) the layers are a molecule in thickness (b) essentially all eddy currents are eliminated or reduced to completely negligible magnitude (c) as a result, the nanocrystalline material does not dissipate magnetic energy from the flux path (d) as a result,... 

---