Nanocrystal

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This article is about crystalline nanoparticles. For other nanocrystalline materials, see Nanocrystalline.

A nanocrystal is a material particle having at least one dimension smaller than 100 nanometres[1] (a nanoparticle) and composed of atoms in either a single- or poly-crystalline arrangement.[2]

The size of nanocrystals distinguishes them from larger crystals. For example, silicon nanocrystals can provide efficient light emission while bulk silicon does not[3] and may be used for memory components.[4]

When embedded in solids, nanocrystals may exhibit much more complex melting behaviour than conventional solids[5] and may form the basis of a special class of solids.[6] They can behave as single-domain systems (a volume within the system having the same atomic or molecular arrangement throughout) that can help explain the behaviour of macroscopic samples of a similar material without the complicating presence of grain boundaries and other defects.[citation needed]

Semiconductor nanocrystals having dimensions smaller than 10 nm are also described as quantum dots.

Synthesis[edit]

The traditional method involves molecular precursors, which can include typical metal salts and a source of the anion. Most semiconducting nanomaterials feature chalcogenide (SS−, SeS−, TeS−) and pnicnides (P3−, As3−, Sb3−). Sources of these elements are the silylated derivatives such as bis(trimethylsilyl)sulfide (S(SiMe3)2 and tris(trimethylsilylphosphine (P(SiMe3)3).[7]

Nanoscale tertiary phosphine-stabilized Ag-S cluster prepared from molecular precursors. Color code: gray = Ag, violet = P, orange = S.[8]

Some procedures use surfactants to solubilize the growing nanocrystals.[9] In some cases, nanocrystals can exchange their elements with reagents through atomic diffusion.[9]

Applications[edit]

Nanocrystals made with zeolite are used to filter crude oil onto diesel fuel at an ExxonMobil oil refinery in Louisiana at a cost less than conventional methods.[10]

See also[edit]

References[edit]

  1. ^ B. D. Fahlman (2007). Material Chemistry. 1. Springer: Mount Pleasant, Michigan. pp. 282–283. 
  2. ^ J. L. Burt (2005). "Beyond Archimedean solids: Star polyhedral gold nanocrystals". J. Cryst. Growth. 285: 681. doi:10.1016/j.jcrysgro.2005.09.060. 
  3. ^ L. Pavesi (2000). "Optical gain in silicon nanocrystals". Nature. 408: 440. doi:10.1038/35044012. 
  4. ^ S. Tiwari (1996). "A silicon nanocrystal based memory". Appl. Phys. Lett. 68: 1377. doi:10.1063/1.116085. 
  5. ^ J. Pakarinen (2009). "Partial melting mechanisms of embedded nanocrystals". Phys. Rev. B. 79: 085426. doi:10.1103/physrevb.79.085426. 
  6. ^ D. V. Talapin (2012). "Nanocrystal solids: A modular approach to materials design". MRS Bulletin. 37: 63. doi:10.1557/mrs.2011.337. 
  7. ^ Fuhr, O.; Dehnen, S.; Fenske, D. (2013). "Chalcogenide Clusters of Copper and Silver from Silylated Chalcogenide Sources". Chem. Soc. Rev. 42: 1871–1906. doi:10.1039/C2CS35252D. 
  8. ^ Fenske, D.; Persau, C.; Dehnen, S.; Anson, C. E. (2004). "Syntheses and Crystal Structures of the Ag-S Cluster Compounds [Ag70S20(SPh)28(dppm)10] (CF3CO2)2 and [Ag262S100(St-Bu)62(dppb)6]". Angewandte Chemie International Edition. 43: 305–309. doi:10.1002/anie.200352351. 
  9. ^ a b Ibanez, M.; Cabot, A. (2013). "All Change for Nanocrystals". Science. 340 (6135): 935–936. doi:10.1126/science.1239221. PMID 23704562. 
  10. ^ P. Dutta and S. Gupta (eds.) (2006). Understanding of Nano Science and Technology (1 ed.). Global Vision Publishing House. p. 72. ISBN 81-8220-188-8. 

External links[edit]