5
Oxide Nanoparticles
R. Seshadri
Abstract
Recent developments in the preparation and use of nanoparticulate oxide materials, more specifically isolated nanoparticles of simple and compound oxides, are
reviewed. While oxide nanoparticles have been known and studied for many decades, it is only in recent years that methods for their preparation have achieved the
level of sophistication which permits monodisperse nanoparticles to be produced
in quantity. In addition, it is only in recent years that the notion of capping of oxide
nanoparticle surfaces by long-chain surfactants, with the corollary that they become soluble, has taken firm hold. The emphasis is on new routes for the preparation of oxide nanoparticles, and how these could be distinct from those used for
metals or chalcogenides. Properties of oxide nanoparticles are discussed with special reference to how they are distinct from the bulk material. Present and possible
applications are discussed in context.
Methods of preparation that are encouraging from the viewpoint of scale-up are
particularly emphasized. Finally, some important issues in the field are outlined.
5.1
Introduction
One of Michael Faraday’s Bakerian Lectures, published as an article in Philosophical Transactions of the Royal Society in 1857 [1] reveals that already in the mid19th century, a great deal of thought had been devoted to what happens to the
properties of materials as their dimensions are made small. Among the materials
investigated by Faraday are the now famous gold sols, which he prepared using a
variety of means. From the colors that Faraday reports, including ruby red, one
infers that he was able to prepare sub-100 nm particles. It would perhaps be proper
to describe Faraday as among the first scientists to attempt a systematic study of
what today would be called a nanomaterial. Nanomaterials have existed for much
longer, an example being Maya blue paint [2], the bright and chemically stable
94
Oxide Nanoparticles
R. Seshadri
Abstract
Recent developments in the preparation and use of nanoparticulate oxide materials, more specifically isolated nanoparticles of simple and compound oxides, are
reviewed. While oxide nanoparticles have been known and studied for many decades, it is only in recent years that methods for their preparation have achieved the
level of sophistication which permits monodisperse nanoparticles to be produced
in quantity. In addition, it is only in recent years that the notion of capping of oxide
nanoparticle surfaces by long-chain surfactants, with the corollary that they become soluble, has taken firm hold. The emphasis is on new routes for the preparation of oxide nanoparticles, and how these could be distinct from those used for
metals or chalcogenides. Properties of oxide nanoparticles are discussed with special reference to how they are distinct from the bulk material. Present and possible
applications are discussed in context.
Methods of preparation that are encouraging from the viewpoint of scale-up are
particularly emphasized. Finally, some important issues in the field are outlined.
5.1
Introduction
One of Michael Faraday’s Bakerian Lectures, published as an article in Philosophical Transactions of the Royal Society in 1857 [1] reveals that already in the mid19th century, a great deal of thought had been devoted to what happens to the
properties of materials as their dimensions are made small. Among the materials
investigated by Faraday are the now famous gold sols, which he prepared using a
variety of means. From the colors that Faraday reports, including ruby red, one
infers that he was able to prepare sub-100 nm particles. It would perhaps be proper
to describe Faraday as among the first scientists to attempt a systematic study of
what today would be called a nanomaterial. Nanomaterials have existed for much
longer, an example being Maya blue paint [2], the bright and chemically stable
94