Nanocrystal

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.

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Synthesis

The traditional method involves molecular precursors, which can include typical metal salts and a source of the anion. Most semiconducting nanomaterials feature chalcogenides (S^S−, Se^S−, Te^S−) 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]

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]

References

^ B. D. Fahlman (2007). Material Chemistry. Vol. 1. Springer: Mount Pleasant, Michigan. pp. 282–283.
^ J. L. Burt (2005). "Beyond Archimedean solids: Star polyhedral gold nanocrystals". J. Cryst. Growth. 285 (4): 681–691. Bibcode:2005JCrGr.285..681B. doi:10.1016/j.jcrysgro.2005.09.060.
^ L. Pavesi (2000). "Optical gain in silicon nanocrystals". Nature. 408 (6811): 440–444. Bibcode:2000Natur.408..440P. doi:10.1038/35044012. PMID 11100719.
^ S. Tiwari (1996). "A silicon nanocrystal based memory". Appl. Phys. Lett. 68 (10): 1377–1379. Bibcode:1996ApPhL..68.1377T. doi:10.1063/1.116085.
^ J. Pakarinen (2009). "Partial melting mechanisms of embedded nanocrystals". Phys. Rev. B. 79 (8): 085426. Bibcode:2009PhRvB..79h5426P. doi:10.1103/physrevb.79.085426.
^ D. V. Talapin (2012). "Nanocrystal solids: A modular approach to materials design". MRS Bulletin. 37: 63–71. doi:10.1557/mrs.2011.337. S2CID 138791528.
^ 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.
^ 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.
^ ^a ^b Ibanez, M.; Cabot, A. (2013). "All Change for Nanocrystals". Science. 340 (6135): 935–936. Bibcode:2013Sci...340..935I. doi:10.1126/science.1239221. PMID 23704562. S2CID 206549388.
^ 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. {{cite book}}: |author= has generic name (help)
^ 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. Bibcode:2013ApSS..279..159L. doi:10.1016/j.apsusc.2013.04.062.
^ "Kenneth Nordtvedt Molecular Hardness - the Genetic Atlas".
^ 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. Bibcode:2016CNan...13...40A. doi:10.2174/1573413712666160530123834.
^ 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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This page was last edited on 3 June 2024, at 00:18

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