A ''nanocrystal'' is a material particle having at least one dimension smaller than 100 nanometres, based on quantum dots (a nanoparticle) and composed of

atoms Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has no neutrons. Every solid, liquid, gas, an ...

in either a single- or

poly- Poly, from the Greek :wikt:πολύς, πολύς meaning "many" or "much", may refer to: Businesses * China Poly Group Corporation, a Chinese business group, and its subsidiaries: ** Poly Property, a Hong Kong incorporated Chinese property devel ...

crystalline arrangement. The size of nanocrystals distinguishes them from larger crystals. For example, silicon nanocrystals can provide efficient light emission while bulk silicon does not and may be used for memory components. When embedded in solids, nanocrystals may exhibit much more complex melting behaviour than conventional solids and may form the basis of a special class of solids. 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. Semiconductor nanocrystals having dimensions smaller than 10 nm are also described as

quantum dot Quantum dots (QDs) are semiconductor particles a few nanometres in size, having light, optical and electronics, electronic properties that differ from those of larger particles as a result of quantum mechanics. They are a central topic in nanote ...

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 Bis(trimethylsilyl) sulfide is the chemical compound with the formula ((CH3)3Si)2S. Often abbreviated ( tms)2S, this colourless, vile-smelling liquid is a useful aprotic source of "S2−" in chemical synthesis. Synthesis The reagent is prepared ...

(S(SiMe₃)₂ and tris(trimethylsilyl)phosphine (P(SiMe₃)₃). Some procedures use surfactants to solubilize the growing nanocrystals. In some cases, nanocrystals can exchange their elements with reagents through atomic diffusion.

Applications

Filter

Nanocrystals made with zeolite are used to filter crude oil into diesel fuel at an

ExxonMobil ExxonMobil Corporation (commonly shortened to Exxon) is an American multinational oil and gas corporation headquartered in Irving, Texas. It is the largest direct descendant of John D. Rockefeller's Standard Oil, and was formed on November 30, ...

oil refinery in Louisiana at a cost less than conventional methods.

Wear resistance

Nanocrystals' level of hardness is closer to the optimized

molecular hardness A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioche ...

which attracts the wear resistance industry

References

External links