Showing posts with label Quantum Dots. Show all posts
Showing posts with label Quantum Dots. Show all posts

Monday, 19 March 2018

Researchers Demonstrate Existence of New Form of Electronic Matter

Electronic Matter
According to the news that has been published in the journal ‘Nature’, engineers based at the University of Illinois have shown that a new form of electronic matter exists. It is called quadrupole topological insulators (QTI).

The properties exhibited by this electronic matter, QTI could bring about a wide range of possibilities in the computer field. It holds great promise in the manufacturing of low-power, robust computers and various devices, that are all defined at the atomic scale.

The topological insulators (TI) are basically electrical insulators on the inside but are conductors along the boundaries. This unique property exhibited by the topological insulators makes them a special type of electronic matter.

A group of electrons form their own phases within the materials. This can be either in the solid, liquid and gas phase, as is seen in water. They can also form an uncommon phase like a topological insulator.

What is this new phase of Electronic Matter? 

The new form of electronic matter is the Quadrupole Topological Insulator. According to theoretical physics, some of the topological insulators have an electrical property known as quadrupole moment.

As we see in a material, the electrons carry a charge. In the process, the material becomes bipolar, that is it contains the positive as well as the negative charge.

Now, in a higher order class of material, we get a quadrupole which is a coupling of two positive and two negative charges. In crystals, the electrons can arrange themselves in such a way that they can give rise to high-order multipoles besides the usual dipole units. In the case of multipoles, four or eight charges are collectively arranged in a unit. The basic forms of multipoles are the quadrupoles wherein two positive and two negative charges are coupled together in a unit.

An analog of a QTI was shown by the researchers of the University of Illinois. They demonstrated it by using a special material from printed circuit boards.

Each circuit has a square of four identical resonators or devices that can absorb electromagnetic radiation at a particular frequency. The boards were positioned in a grid to form the crystal analog.
Each of these resonators behaves like an atom and the connections between the resonators act as bonds between these atoms.

The system is then subjected to microwave radiation to measure the amount that has been absorbed by each of the resonators. This in turn will indicate the behavior of the electrons in an analogous crystal. If the microwave radiation absorbed by a resonator is more, then there are higher chances of finding an electron on the corresponding atom.

In the above experiment it was inferred that the corners of the connected resonators absorbed the microwave radiation at a specific frequency whereas the rest of the units did not do so. The researchers then separated the bottom row from the grid and on subjecting it to the microwave radiation, it was noticed that the next highest rows showed the topological effects on absorbing the radiation.

They concluded that the edges of a QTI are not conductive unlike that seen in a TI. It was only the corners which are active and they correspond to the four localized point charges that form the quadrupole moment.

On measuring the amount of microwave radiation each of the resonators absorbed in the QTI, it was confirmed that the resonant states was in a particular frequency range and localized in the four corners. This shows the existence of predicted protected states that would be filled up by electrons that would in turn form four corner charges.

With the experiment conducted, scientists are beginning to understand the possibilities of the new electronic matter and its application. As of now, the physicists can predict that the new form of electronic matter exists, but no material has been found to have these properties.

Tuesday, 8 September 2015

Quantum Dot Technology May Help Light the Future


Quantum Dots – New Generation LED Lighting

Developments at the Oregon State University, in the manufacturing technology for quantum dots could soon lead to new generation of LED lighting.Quantum dots are nanoparticles which could be utilised in emitting light and by accurately controlling the size of the particle and the colour of the light.

They have been utilised for some time and can be expensive, lacking optimal colour control. The manufacturing technique that have been developed at OSU would be able to increase to large volumes for low-cost commercial applications providing new ways of offering the accuracy essential for better colour control.

This could create a more user friendly white light while utilising less toxic material together with low cost manufacturing procedures which tend to take advantage of simple microwave heating. It would help the country in reducing its lighting bill in half.

Compared to the cost of incandescent as well as fluorescent lighting and the cost, performance and environmental improvements could eventually create solid state lighting systems which consumers prefer and help the nation in reducing its lighting bill by half, according to researchers.

Same technology could also be merged in improved lighting display, computer screens, televisions, smart phones and the other systems.

Applied to Various Products & Technologies

Significant to the advances that had been published in the Journal of Nanoparticle Research, is use of both a continuous flow chemical reactor and microwave heating technology that is theoretically identical to the ovens which are part of every modern kitchen.

The constant flow system tends to be fast, cheap, energy efficient and would cut manufacturing costs. Microwave heating technology could report a problem that had held back wider use of these systems, so far, which is the accurate control of heat needed during the procedure.

Microwave approach would translate into development of nanoparticles that are exactly the right size, shape and composition. According to an associate professor and chemical engineering in the OSU College of Engineering, Greg Herman, states that `there are various products and technologies that quantum dots can be applied to but for mass consumer use, possibly the most important is improved LED lighting.

Eventually they would be able to manage in producing low cost, energy efficient LED lighting with the soft quality of white light which people would want and at the same time the technology would use nontoxic materials and reduce the waste of materials which are used and translates to lower cost and environmental protection.

Research Supported by Oregon BEST/National Science Foundation

According to Herman, some of the top existing LED lighting being produced presently at industrial levels tend to use cadmium which is highly toxic and the system now being tested and developed at the OSU depends on copper indium diselenide which is a much more benign material with high energy conversion efficiency.

Some earlier systems creating these nanoparticles for use in optics, electronics and biomedicine tend to be slow, expensive and at times toxic as well as often a waste. There is also a possibility of other applications of these systems. Cell phones and portable electronic devices could use less power and could last longer on a single charge.

`Tuggants or compounds with certain infrared or visible light emissions could be utilised for accurate and prompt identification which include control of counterfeit bills or products. OSU has been working with private sector in the development of this technology. The research is being supported by Oregon BEST and the National Science Foundation Centre for Sustainable Materials Chemistry.

Sunday, 13 April 2014

Recharge Your Smartphone in 30 Seconds with Quantum Dots!

An Israeli startup unveils a new generation of battery -based organic nanoparticles with quantum properties. Video demo of a new generation of battery manufactured by the company StoreDot is the buzz on the web. It shows that a Smartphone can be recharged in 30 seconds of time duration. If you consider today’s recharging time of several hours to reach a full charge, this is a boon to a Smartphone user.

However, you cannot expect to fit your phone tomorrow with this new technology, which will not be sold within 3 years. At this point, the video depicts a prototype, too bulky to attach to the inside of the Smartphone. It remains that this new technology could be promising. This is at least what seems to think Samsung, which is currently in talks with the start -up.

Made from compounds of semi conductors, these "quantum dots" manage to confine electrons and holes (electrons location having been previously dislodged) in a confined space in three dimensions, of the order of several tens of nanometers. This assembly is sometimes having their name “artificial atoms “. Their optical and electronic properties are already used in many applications like transistor, LED, medical imaging, solar energy production and many more.

Usually, the quantum dots are synthesized from inorganic materials often based on the elements like arsenic, gallium and selenium. Now StoreDot offers for the first time to use peptides - these organic molecules formed as amino acids, the building blocks of proteins. According to Gil Rosenman, director of research belongs to StoreDot; these peptides spontaneously assemble to form quantum dots under certain conditions.

And those peptides can behave as semiconductors. The advantage of peptide chains is that they are easy and inexpensive to synthesize. Moreover, these quantum dots are made "from amino acid naturally produced by plants and animals, they should therefore not be too harmful to the environment. These are unlike to that of most inorganic quantum dots, especially those made from heavy metals.

This is a remarkable discovery, they add, as well as large organic molecules conduct electricity is well known but nobody had considered that biological peptides can behave as semiconductors. According StoreDot, new batteries boosted biological Nanoparticles could take five days to drain instead of one day for a conventional batteries.

And 7 minutes of charge is sufficient to use your Smartphone for 24 hours. Besides, according to Gil Rosenman, the life of the battery would be significantly extended. This is due to their crystalline form, quantum dots could remain for thousands of charge cycles it seems.