Zero dimensional nanomaterials

Analogous to the period in this sentence, a zero-dimensional structure is the simplest building block that may be used for nanomaterials design. These materials have 

A special case of nanocrystal that is comprised of a semiconductor is known as a quantum dot Typically, the dimensions of these nanostructures lie in the range 1-30 nm, based on its composition (see below). Quantum dots currently find applications as sensors, lasers, and LEDs. In fact, new high-density disks (e.g., HD-DVD and Blu-ray high-definition DVD formats) may only be read via blue lasers, which 

OD nanostructures of a homogeneous size distribution.By contrast, nanoparticles exhibit a greater range of sizes/shapes. l Nanocrystals are characterized by the presence of an ordered lattice array of the constituent subunits, as illustrated by a single nanocrystal of CdSe. l In stark contrast to a nanocrystal, an example of a nanopowder is shown that consists of microscopic grains, each comprised of nanoscale amorphous units.Xhe size regime that is intermediate between the nano- and microregimes is best referred to as submicron, The bulk powder scale bar is 200 pm. 

Size 1-100 nm (nanoclusters 1-10 mn) Homogeneous molecular composition 15% Size dispersion (less polydispersity for nanoclusters relative to nanoparticles) 

Reproducible synthesis (control over size, shape, and composition) 

Soluble in polar/nonpolar organic solvents (depending on stabilizing agent) 

A special case of nanocrystal that is comprised of a semiconductor is known as a quantum dot (QD). Typically, the dimensions of these nanostructures lie in 

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The simplest way to classify nanomaterials used in combination with liquid crystal materials or the liquid crystalline state is by using their shape. Three shape families of nanomaterials have emerged as the most popular, and sorted from the highest to the lowest frequency of appearance in published studies these are zero-dimensional (quasi-spherical) nanoparticles, one-dimensional (rod or wirelike) nanomaterials such as nanorods, nanotubes, or nanowires, and two-dimensional (disc-like) nanomaterials such as nanosheets, nanoplatelets, or nanodiscs. 

The aforementioned frequency of the use of these nanomaterial shapes is best attributed to two factors (1) the ease with which these nanoparticle shapes can be synthesized in the laboratory and (2) the availability of these nanomaterials from commercial sources. It cannot be the aim of this review to cover all of the different nanomaterials used so far, but some of the most commonly investigated will be introduced in more detail. For zero-dimensional nanoparticles, emphasis will be put on metallic nanoparticles (mainly gold), semiconductor quantum dots, as well as magnetic (different iron oxides) and ferroelectric nanoparticles. In the area of onedimensional nanomaterials, metal and semiconductor nanorods and nano wires as well as carbon nanotubes will be briefly discussed, and for two-dimensional nanomaterials only nanoclay. Finally, researchers active in the field are advised to seek further information about these and other nanomaterials in the following, very insightful review articles [16, 36-45]. 

Synthesis forms a vital aspect of the science of nanomaterials. In this context, chemical methods have proved to be more effective and versatile than physical methods and have therefore, been employed widely to synthesize a variety of nanomaterials, including zero-dimensional nanocrystals, one-dimensional nanowircs and nanotubes as well as two-dimensional nanofilms and nanowalls. Chemical synthesis of inorganic nanomaterials has been pursued vigorously in the last few years and in this article we provide a perspective on the present status of the subject. The article includes a discussion of nanocrystals and nanowires of metals, oxides, chalcogenides and pnictides. In addition, inorganic nanotubes and nanowalls have been reviewed. Some aspects of core-shell particles, oriented attachment and the use of liquid-liquid interfaces are also presented. 

Nanotechnology development has allowed that nanomaterials can be used in biomedical applications, and nanometer sized objects can interact with biological entities like cells, virus, protein, enzyme, etc. For this reason, many research projects has been focused in the development of nanosystems, nanoparticles and nanodevices for this applications. This area is relatively new, according to the ISI web of knowledge, the publications of the nanoparticles for biomedical applications started on 2000 year, and since that time they have increased exponentially (Figure 1). The nanoparticles (NPs) used for biomedical purposes generally include zero-dimensional nanospheres and one-dimensional nanowires and nanotubes. 

Even though the expressions nanomaterials or nanocomposites are recent (and very successful), these industrial materials have existed for at least a century and apparently always existed in nature (in minerals and vegetables). These small particles range in size from a few to several tens of nanometres and are called quasi zero-dimensional mesoscopic systems, quantum dots, quantized or Q particles, etc According to Jordan et al. nano-sized inclusions are defined as those that have at least one dimension in the range 1 100 mn. In materials research, the development of polymer nanocomposites is rapidly emerging as a multidisciplinary research activity whose results could broaden the applications of polymers to the great benefit of many different industries. 

The class of nanomaterials that maybe termed zero-dimensional comprise systems that are confined within up to several hundreds of nanometers in aU three dimensions. Although there exists no clear-cut size threshold at which a system switches from a zero-dimensional system to bulk, there is a rather weU-defined class of systems that fit the above definition with unique and intriguing properties. The most commonly studied zero-dimensional systems are quantum dots, nanoparticles (or clusters), and cage-like structures. In this section, we shall begin with an overview of methods used to study such materials. 

In addition to structural and electronic properties that are explored in zero-dimensional materials, one-dimensional materials also exhibit rather interesting elastic properties. We shall begin this section with a brief review of elastic considerations regarding one-dimensional nanomaterials and afterward move onto structural and electronic properties. 

Cao, G. 2004. Zero-dimensional nanostructures NPNPs. In Nanostructures Nanomaterials Synthesis, Properties, and Applications, pp. 51-109. London, U.K. Imperial College Press. 

Zero-, one-, and two-dimensional CNMs have attracted the attention of researchers. These include fullerenes, carbon nanofibers, carbon nanotubes, and graphene. The advancements in the various synthesis procedures have envisaged the preparation of various CNMs with different shapes and sizes. Nanotechnology has paved the way to utilize these nanomaterials either individually or as nanocomposites for cutting-edge applications in chemical industry, materials science, biology, medicine, and other sectors. 

As known, solid nanomaterials have unusual, unique physical and chemical properties. They contain structural elements, whose geometrical sizes, if only in one dimension, do not exceed the value ho=100 nm it is, first of all, nanoparticles (zero-dimentional elements) and nanofilms (two-dimensional elements). 

Nanomaterials can be classified as zero- (OD), one- (ID) and two-dimensional (2D) materials based on their size. OD nanomaterials are composed of a limited number of atoms (usually under 100). They are nanomaterials that have all the dimensions (x-y-z) in the nanoscale. ID nanomaterials have a large aspect ratio and have at least one dimension greater than nanoscale (for instance nanotubes with diameter in nanoscale and length on the micron scale). 2D nanomaterials have at least two dimensions on the micron scale, for instance, nanoplatelets and nanoribbons with length, breadth, or diameter on the micron scale. 2D nanomaterials are generally sheets, ribbons, or platelets with a nanoscale thickness (z). 

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