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Introduction to oxide nanoparticles

The most widespread route to fabrication of metal oxide nanoparticles involves the “bottom-up” approach involving the precipitation from aqueous solution from metal salts. Organometallic species can also be used, but due to their cost and the difficulty in manipulating these compounds, they are used less frequently. An alternative “top-down” approach has been demonstrated for aluminum and iron oxide nanoparticles; however, it is possible that this methodology could be extended to other oxides.

From molecular species to nanoparticles

Hydroxide, oxyhydroxide or hydrated oxide solid phases obtained via precipitation are made of particles whose average size may range from a few nanometers to a few microns. Particle morphology may vary depending on synthesis conditions. Moreover, aging in aqueous solution may bring about significant dimensional, morphological and structural changes.

Use of metal salts

The dissolution of metal salts in water results in the formation of solvated coordination compounds in which the chemistry of such complexes, and especially their acid behavior, provides a framework for understanding how the solid (oxide) forms via polycondensation. The binding of water molecules to the metal cation results in the increase in the acidity such that they tend to be deprotonate spontaneously according to the hydrolysis equilibrium

[M(H 2 O) n ] z+ + h H 2 O → [M(OH) h (H 2 O) n-h ] (z-h)+ + h H 3 O +

or by the neutralisation with a base,

[M(H 2 O) n ] z+ + h HO- → [M(OH) h (H 2 O) n-h ] (z-h)+ + h H 2 O

in which h is the hydroxylation ratio of the cation. The resulting hydroxylated complexes condense via two basic mechanisms of nucleophilic substitution, depending on the nature of the coordination sphere of the cations. Condensation of aquohydroxo complexes proceeds by elimination of water and formation of hydroxo bridges (olation), while for oxohydroxo complexes, condensation proceedes via the formation of oxo bridges (oxolation).

In order to understand how small particles form and what role the experimental parameters play on their characteristics and on evolution, it is useful to review the kinetic aspects of condensation reactions. The precipitation of a solid involves four kinetic steps.

  1. Formation of the zero-charge precursor. [M(OH) z (H 2 O) n-z ] 0 , which is able to condense and form a solid phase.
  2. Creation of nuclei, through condensation of zero-charge precursors.
  3. Growth of the nuclei through addition of matter, until the primary particle stage is reached.
  4. Nucleation and growth steps form particles under kinetic control following a reaction path of minimum activation energy under conditions imposed to the system (acidity, concentration, temperature), but the products are not necessarily thermodynamically stable.

Aging of the suspensions, which may take place over a long time scale (hours, days or months), allows the system to tend toward, or reach stability, and it is often associated with modifications of some physical or chemical characteristics of the particles.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe

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Source:  OpenStax, Nanomaterials and nanotechnology. OpenStax CNX. May 07, 2014 Download for free at http://legacy.cnx.org/content/col10700/1.13
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