Nanophase materials

Brus L E 1993 NATO ASI School on Nanophase Materials ed G C Had]lpanayls (Dordrecht Kluwer) Allvisatos A P 1996 Semiconductor clusters, nanocrystals and quantum dots Science 271 933 Heath J R and Shlang J J 1998 Covalency In semiconductor quantum dots Chem. See. Rev. 27 65 Brus L 1998 Chemical approaches to semiconductor nanocrystals J. Phys. Chem. Solids 59 459 Brus L 1991 Quantum crystallites and nonlinear optics App/. Phys. A 53 465... 

Qlynick D L, Gibson J M and Averback R S 1998 Impurity-suppressed sintering in copper nanophase materials Phii. Mag. A 77 1205... 

Siegel, R.W. (1996, December) Creating nanophase materials. Scientific American21S, 42. 

T. G. Nieh, J. Wadsworth, and K. Higashi, "High Strain Rate Superplasticity in Metals and Composites," in Transaction of the Materials Research Society of Japan Vol 16B - Composites, Grain Boundaries and Nanophase Materials, pp. 1027-1032, M. Sakai, M. Kobayashi, T. Suga, R. Watanabe, Y. Ishida, and K. Niihara ed., Elsevier Science, Netherland, (1994). 

Z. L. Wang, Characterization of Nanophase Materials, Wiley-VCH, New York, 2000. 

Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA... 

Work at BNL was supported by the US Department of Energy, Divisions of Chemical and Material Sciences, under Contract DE-AC02-98CH10886. Work at ORNL was conducted at the Center for Nanophase Materials Sciences and was sponsored by the Division of... 

Hydrothermal synthesis is a powerful method used for the fabrication of nanophase materials due to the relatively low temperature during synthesis, facile separation of nanopartides in the product, and ready availability of apparatus for such syntheses. Versatile physical and chemical properties of nanomaterials can be obtained with the use of this method that involves various techniques (e.g., control of reaction time, temperature and choice of oxidant and its concentration). Several extensive reviews are available that discuss the fundamental properties and applications of this method [2, 3]. These reviews cover the synthesis of nanomaterials with different pore textures, different types of composition [2, 4—6], and different dimensionalities in terms of morphology [6-8]. 

Meldrum, F.C., Wade, V.J., Nimmo, D. L., Heywood, B.R. and Mann, S. (1991) Synthesis of inorganic nanophase materials in supramolecular protein cages. Nature, 349, 684-687. 

Nanophase materials are prepared by compacting the nanosized clusters generally under high vacuum. Synthesis of such nanomaterials has been reported in a few systems. The average grain sizes in these materials range from 5 to 25 nm. 

Hadjipanyas, G. Siegel, R. W. (1994) Nanophase Materials Synthesis, Properties and Applications, Kluwer, Holland. 

Siegel, R. W., Cluster assembled nanophase materials. Annu. Rev. Mater. Sci. 21, 559 (1991). 

Siegel, R. W., and Hahn, H., Nanophase materials, in Current Trends in the Physics of Materials (M. Yussouff, Ed.), p. 403, World Scientific, Singapore (1987). 

Fig. 9. Theoretical predictions of changes in surface properties of nanophase materials that affect the hydroxide layer. Compared to (a) conventional materials, (b) nanophase materials possess higher surface area and less acidic OH- groups (due to an increase in electron delocalization) in the hydroxide layer. (Adapted and redrawn from Klabunde et al, 1996.)...

As the disciplines of cell-tissue engineering and nanophase material science develop and mature, the preceding design criteria will be expanded and refined. Undoubtedly, nanophase ceramics have great potential to become the next generation of choice proactive biomaterials for innovative biotechnology and biomedical applications that could have profound clinical impact. 

Siegel, R. W., andFougere, G. E., Mechanical properties of nanophase materials, in Nanophase Materials Synthesis-Properties-Applications (G. C. Hadjipanayis andR. W. Siegel, Eds.), p. 233. Kulwer, Dordrecht, 1994. 

The filling control approach has even been applied to some nanophase materials. For example, the onset of metallicity has been observed in individual alkali metal-doped single-walled zigzag carbon nanotubes. Zigzag nanotubes are semiconductors with a band gap around 0.6 eV. Using tubes that are (presumably) open on each end, it has been observed that upon vapor phase intercalation of potassium into the interior of the nanotube, electrons are donated to the empty conduction band, thereby raising the Fermi level and inducing metallic behavior (Bockrath, 1999). 

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