Nanocrystalline composites

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]. 

Sarangi, S. N. and Sahu, S. N. (2004). CdSe nanocrystalline thin films composition, structure and optical properties. Physica E, 23,159-167. 

Veprek, S., Nesladek, P., Niederhofer, A., Glatz, F., Jilek, M., and Sima, M., "Recent Progress in the Superhard Nanocrystalline Composites Towards Their Industrialization and Understanding of the Origin of the Superhardness, Surf. Coat. Technol,Vo. 108/109,1998,pp. 138-147. 

Nanostructured materials are nothing new. Chrysotile fibers are an example (Fig. 16.22), as are bones, teeth and shells. The latter are composite materials made up of proteins and embedded hard, nanocrystalline, inorganic substances like apatite. Just as with the imitated artificial composite materials, the mechanical strength is accomplished by the combination of the components. 

Han, J.K., Choi, S.M. and Lee, G.H. (2007) Synthesis and photocatalytic activity of nanocrystalline Ti02-SrO composite powders under visible lightirradiation. Materials Letters, 61, 3798-3801. 

S. Veprek, P. Nesladek, A. Niederhofer, and F. Glatz, Search for Superhsrd Materials Nanocrystalline Composites with Hardness Exceeding 50GPa , NanoStructured Mater., 10,679 (1998). 

S. Bharathi and O. Lev, Sol-gel-derived nanocrystalline gold-silicate composite biosensor. Anal. Commun. 35, 29-31 (1998). 

Figure 5 shows the absorption and desorption kinetics of nanocrystalline MgH2 with ceramic catalysts at 300°C. The BCN catalyst addition was very effective to enhance the desorption kinetics in comparison to pure MgH2 and SDC added composite. 

Fig. 7. Scanning electron micrographs of (a) magnesium hydride (MgH2) before milling and (b) nanocrystalline MgH2 - SDC lmol% composite after milling.

The progress of hydrogen storage and its container materials were reviewed. AB2 nanocrystalline alloy, Ti-NaAlH4 complex hydride and Mg/MWNTs composite are promising hydrogen storage materials. 

Figure 29. Fiuman osteoblast-like MG 63 cells in cultures on material surfaces modified with carbon nanoparticles. A fullerene Cgo layers deposited on carbon fibre-reinforced carbon composites (CFRC), B fullerene C o layers deposited on microscopic glass coverslips, C terpolymer of polytetrafluoroethylene, polyvinyldifluoride and polypropylene, mixed with 4% of single-wall carbon nanohorns, D the same terpolymer with high crystalline electric arc multi-wall nanotubes, E diamond layer with hierarchically organized micro- and nanostmcture deposited on a Si substrate, F nanocrystalline diamond layer on a Si substrate. Standard control cell culture substrates were represented by a PS culture dish (G) and microscopic glass coverslip (FI). Immunofluorescence staining on day 2 (A) or 3 (B-Fl) after seeding, Olympus epifluorescence microscope IX 50, digital camera DP 70, obj. 20x, bar 100 pm (A, C, D, G,H)or 200 pm (B, E, F) [16].

Poznyak SK, Xalpin DV, Kulak A1 (2001) Structural, optical and photoelectrochemical properties of nanocrystalline Xi02-ln203 composite solids and films prepared by sol-gel method. J Phys Chem B 105 4816-4823... 

Studies of the kinetics and photoelectrochemistry of nanocrystalline composite films of CdS/Ni in aqueous sulfite [180] and thin film CdS/electrolyte interface were carried out [181]. 

---