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Tuning nanomaterials

Nanostructured materials can be tuned to achieve improved mechanical, electrical, optical, magnetic and other functional properties. Tailored and Tuneable properties of nanomaterials represent an important and integral part of technological developments and are now essential for future applications in the current industrial manufacturing. For example nanomaterials play a high role in today's electronic devices ranging from transistors all the way to lasers and solar-energy conversion devices or the particles could be used as a switch in an optical circuit by precisely tuning the optical properties.
Tuning or tailoring
Many different areas ranging from energy to transportation or health require specific nano-structured materials with improved functionality and reliability for the use in applications such as sensors and actuators, printable electronics, high frequency devices, friction coatings, and others. For this, two different approaches are used, namely tailoring materials on the nano-scale and develop tuneable materials.
Tuning can be achieved in many ways using electric field, electric, chemical and electrochemical gating, temperature or light in metals and ceramics to get desired mechanical, electrical, dielectric, optical and magnetic properties.By integrating defects using dopants, point defects, dislocations and interfaces and by the control of composition and phases of materials the nanostructure can be tailored to obtain optimized properties and combinations of properties. Such approach is used for the development of materials that are far from equilibrium. As they contain large fractions of defects and disorder, the properties are directly governed by the structure.An alternative approach employs external fields to tune materials, i.e. change their properties in a reversible and reproducible manner, via modification of the electronic structure. Depending on the materials and structures or morphologies employed. Two such approaches are given below.
Coated gold nanorods
Researchers have made gold nanorods coated with silver selenide or silver sulphide (silver chalcogenides) by chemically plating the gold surface with silver and then exposing it to sulphide or selenide in an oxidising environment. Thus the resonance frequency gold nanorods can be tuned between 600 nanometres (visible light) to 2000 nanometres (infrared light). Varying the thickness of the silver chalcogenide layer changes the resonance frequency of the particles and gives the material its on-off switch effect, the lack of such a switching unit has so far limited the development of integrated nanophotonic devices. Researchers feel that production of metal nanorods with a uniform and controlled semiconductor coating is a significant synthetic achievement which may lead to the development of new devices.
Application of pressure
Researchers of Lawrence Livermore National Laboratory have developed a technique to tune nanomaterials and their fundamental properties only by applying pressure. Researchers packed quantum dot which is semiconducting materials that has its electrons confined in all three spatial dimensions into highly compacted materials gives rise to quantum dot solids, materials that present particle-particle coupling as well as electronic properties characteristic to both individual and collective particles. Researchers state that high pressure provides insight into the fundamental properties of nanoparticles, which can be drastically different from the corresponding bulk material.

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