Physics:Nanocrystal

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A nanocrystal is a material particle having at least one dimension smaller than 100 nanometres, based on quantum dots[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

The traditional method involves molecular precursors, which can include typical metal salts and a source of the anion. Most semiconducting nanomaterials feature chalcogenides (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(trimethylsilyl)phosphine (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

Filter

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

Wear resistance

Nanocrystals' level of hardness[11] is closer to the optimized molecular hardness[12] which attracts the wear resistance industry[13][14]

See also

References

  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 (4): 681–691. doi:10.1016/j.jcrysgro.2005.09.060. Bibcode: 2005JCrGr.285..681B. 
  3. ↑ L. Pavesi (2000). "Optical gain in silicon nanocrystals". Nature 408 (6811): 440–444. doi:10.1038/35044012. PMID 11100719. Bibcode: 2000Natur.408..440P. 
  4. ↑ S. Tiwari (1996). "A silicon nanocrystal based memory". Appl. Phys. Lett. 68 (10): 1377–1379. doi:10.1063/1.116085. Bibcode: 1996ApPhL..68.1377T. 
  5. ↑ J. Pakarinen (2009). "Partial melting mechanisms of embedded nanocrystals". Phys. Rev. B 79 (8): 085426. doi:10.1103/physrevb.79.085426. Bibcode: 2009PhRvB..79h5426P. 
  6. ↑ D. V. Talapin (2012). "Nanocrystal solids: A modular approach to materials design". MRS Bulletin 37: 63–71. doi:10.1557/mrs.2011.337. https://zenodo.org/record/898757. 
  7. ↑ Fuhr, O.; Dehnen, S.; Fenske, D. (2013). "Chalcogenide Clusters of Copper and Silver from Silylated Chalcogenide Sources". Chem. Soc. Rev. 42 (4): 1871–1906. doi:10.1039/C2CS35252D. PMID 22918377. 
  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 (3): 305–309. doi:10.1002/anie.200352351. PMID 14705083. 
  9. ↑ 9.0 9.1 Ibanez, M.; Cabot, A. (2013). "All Change for Nanocrystals". Science 340 (6135): 935–936. doi:10.1126/science.1239221. PMID 23704562. Bibcode: 2013Sci...340..935I. 
  10. ↑ P. Dutta and S. Gupta (eds.) (2006). Understanding of Nano Science and Technology (1 ed.). Global Vision Publishing House. pp. 72. ISBN 81-8220-188-8. 
  11. ↑ Liu, Xiaoming; Yuan, Fuping; Wei, Yueguang (August 2013). "Grain size effect on the hardness of nanocrystal measured by the nanosize indenter". Applied Surface Science 279: 159–166. doi:10.1016/j.apsusc.2013.04.062. Bibcode: 2013ApSS..279..159L. 
  12. ↑ "Kenneth Nordtvedt Molecular Hardness - the Genetic Atlas". https://www.thegeneticatlas.com/Kenneth-Nordtvedt-Molecular-Hardness.htm. 
  13. ↑ Alabd Alhafez, Iyad; Gao, Yu; M. Urbassek, Herbert (30 December 2016). "Nanocutting: A Comparative Molecular-Dynamics Study of Fcc, Bcc, and Hcp Metals". Current Nanoscience 13 (1): 40–47. doi:10.2174/1573413712666160530123834. Bibcode: 2016CNan...13...40A. 
  14. ↑ Kaya, Savaş; Kaya, Cemal (May 2015). "A new method for calculation of molecular hardness: A theoretical study". Computational and Theoretical Chemistry 1060: 66–70. doi:10.1016/j.comptc.2015.03.004. 

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