CNT applications

Air and Water Filtration
Biomedical Applications
Catalyst Supports
Ceramic Applications
Conductive Adhesives
Conductive Plastics
Energy Storage
Fibres and Fabrics
Field Emission Applications
Investment casting
Metal Moulding
Molecular Electronics
Structural Composites
Thermal Conductivity
Thermal Materials

still more are there.....counting

My new paper in Electronics Letters.

Transient analysis of mixed carbon nanotube bundle interconnects
Abstract

Presented for the first time is an accurate modelling hierarchy for mixed CNT bundle interconnects. Single-walled CNTs and multi-walled CNTs have been modelled as equivalent single conductor transmission lines and then combined to form a mixed CNT bundle interconnect, which is basically a multiple equivalent single conductor model. Two multiple equivalent single conductor interconnects have been taken to form the multiconductor transmission line model. The delays from transient analysis for both models for a unit bundle have been compared with the corresponding ones for SWCNT bundles and MWCNTs that exist in the literature. It is found that mixed CNT bundle interconnects are superior to both SWCNT bundle and MWCNT interconnects in terms of delay.

citation this article as:
P. Uma Sathyakam and P.S. Mallick, 'Transient analysis of mixed carbon nanotube bundle interconnects', Electronics Letters, IET, Vol. 47(20), pp. 1134-1136.

Carbon nanotube composites for enzymes and cosmetics

Hiroyuki Muto and colleagues at Japan's Toyohashi University of Technology (Toyohashi Tech) have developed an innovative method for producing CNT (carbon nano-tube) resin composite material that only requires 1/100 of the conventional amount of CNT additive to produce electrical conductivity in the composite material.

 

In this method, CNTs were mixed in an electrolyte solution and added to the composite, where the CNTs were absorbed onto the surfaces of the resin particles due to electrostatic absorption. This innovative procedure enabled the production of electrical conducting composites by the addition of a small quantity of CNTs.

 

Importantly, the electrical conductivity of the composite material was easily controlled by changing the amount of electrolyte added to the composite; namely, the concentration of CNTs absorption onto the resin particles.

 

Notably, this approach enables significant reductions in both the production costs and the production time compared with conventional methods for manufacturing conductive resins.

 

The researchers are confident that adding particles with charged surfaces will enable the production of a wide range of composite materials such as metals, ceramics, and polymers. This method is expected to find applications in the production of enzymes and cosmetics.

Adventures of electronics

Microelectronics is in expectation of miracles. Discovery of the giant magnetoresistance phenomenon, thanks to which the HDD capacity has increased by a factor of a hundred at once, has inspired researchers for new exploits, specifically for search of an appropriate RAM replacement. If this task is solved, habitual equipment will change drastically, for example, a switched-on computer will start working from the “interrupted point” without waiting and loading. The future of microelectronics as it is considered by the world science, and the Russian researchers’ contribution to the progress is discussed in the interview with the vice-chancellor of Moscow State Technical University of Radio Engineering, Electronics and Automation Alexander Morozov.

Alexander Morozov: “It is great luck to find an area where you will be the first to get interesting and important results. I have been in the physical science for 36 years, and I came across only five or six zests like this throughout this period. Frustration is one of them.”

Alexander Igorevich, electronic industry is taking in scientific theories and developments very quickly, so researchers probably know better than all analysts what the industry future may hold. What changes are most likely and expected?
– This is indeed a thriving industry. If in the early 90s of the last century, the HDD capacity of our personal computers was about a hundred megabytes, by the mid-90s it increased by ten times, after which it grew quickly up to a hundred Gigabytes. Nowadays, the HDD capacity is coming closer to a Terabyte. This qualitative leap happened owing to giant magnetoresistance discovery made in 1988 by scientific groups under the guidance of a French physicist Albert Fert and a German physicist Peter Grunberg, who were awarded the Nobel Prize for this discovery in 2007 году. The industry immediately grasped the discovery, it seems to me, even quicker than physicists finally comprehended it. The companies that produce HDDs made new playback heads (which were more sensitive to the magnetic field) and smaller tracks on the disk. The outcome was as follows – much more information could be recorded on the same area of HDD, the HDD capacity has increased by a factor of a hundred at once. Naturally, this resulted in magnetoelectronics boom. New active research started, in the course of which other effects were found in the framework of this discovery. First of all – the possibility to create magnetic nonvolatile memory (NVRAM), which will probably come soon to replace current RAM. Nowadays, when the computer is switched on, everything is deleted from the RAM, and switching requires access again to a relatively slow hard disk drive, i.e. it is time-consuming. Should a new memory be in place, there will be no such inconveniences: after switching, the computer will start working from the place it stopped without any loading and waiting. In the future, such memory will replace the HDD and flash memory. A natural question arises: why this has not happened so far? The point is that this memory (MRAM or magnetoresistive memeory) is rather difficult to fit into an ordinary technological chain based on application of silicon semiconductors. Besides, it is very expensive, about a hundred times more expensive than the RAM is. Naturally, nobody would agree to its implementation in production quantities so far. Anyway, pathfinders have already appeared, specifically Motorola has already used it in its cell phones via making the MRAM-based memory chip. To make the technology popular, it should be got into shape, the cost should be decreased, and it should be adapted to existing technologies.
What is the contribution to the progress made theorists at Moscow State Technical University of Radio Engineering, Electronics and Automation, who are not bound either to experimentalists or to the industry?
– Yes, we are exclusively making theoretical study. As the above-mentioned technologies have not become widespread in Russia – neither HDDs or MRAM are produced in our country, as far as I know, indeed, we are not bound to anybody. We are studying magnetic nanostructures, where the giant magnetoresistance effect was discovered. Such elementary structure consists of two ferromagnetic metal layers separated by a layer of nonmagnetic or antiferromagnetic metal, and it is called a “spin valve”. It has turned out that roughness of interface between layers, the thickness of which being about one nanometer, cardinally influences their magnetic properties. Only theorists prefer to believe that boundaries are ideally smooth. But this is not the case in real life. Prior to our research commencement, it was known that presence at the interface of ferromagnetic and antiferromagnetic layers of atomic steps, changing the layer thickness by one atomic plane, led to appearance of frustration in the interlayer exchange interaction. At that, homogeneous distribution of magnetic parameters of order does not meet the minimum energy. Our research group pursued the following aim – to predict what distribution of magnetic parameters of order in the space will appear depending on the layer thickness and the distance between atomic step edges at the interface. The aim was successfully achieved for the case of two-layer ferromagnetic-antiferromagnetic nanostructures and spin-valve structures with an antiferromagnetic interlayer. We have been the first to solve this interesting basic task. Why is it needed from the practical point of view? Knowing phase diagram enables (via correct selection of technological parameters) to obtain the roughness of interface boundaries, which would ensure optimal characteristics of a given magnetoelectronic device. Of course, this requires enormous technologists’ work, however, without our theoretical calculations at hand, a technologist can carry out this search only by trial and error, i.e., by the hit-and-miss method.
How did the world scientific community apprehend your theories?
– The researchers working in this area acknowledge our priority. Specifically, we have predicted a new type of domain walls – frustration-caused domain walls. Their thickness has turned out to be significantly smaller than that of traditional domain walls, besides, it changed according to moving away off the interface boundary. Our work was published in 1998 at the domestic “Journal of Experimental and Theoretical Physics”. We persuaded experimentalists for a long time to verify our theory, but this required the nanometer resolution for magnetic properties investigation. Our colleagues had no such possibilities as a rule. At last, in 2004, the US journal Physical Review Letters published works by German researchers at the Max Planck Institute for Physics of Microstructures, Halle (Max-Planck-Institut fur Mikrostrukturphysik, Halle), where our predictions had been experimentally confirmed. The German researchers had not, in all probability, read our article, although the “Journal of Experimental and Theoretical Physics” is translated into English, therefore, they did not refer to our research right away, but only after we pointed to our publication.
A group of Italian researchers at the Polytechnic Institute of Milan experimentally discovered discretization of ferromagnetic layers in the “ferromagnetic–antiferromagnetic oxide–ferromagnet” nanostructures into nanodomains, as well as transition from a nanodomain state to a homogeneous state accompanied by the layer thickness change. They found only one theory that explained the observed phenomena – our theory, and they actively refer to us.
We can also be proud that we were invited to write chapters for two monographies published in the US and Germany, that were dedicated to giant magnetoresistance and antiferromagnetic oxide properties. It is interesting to note that we did not perform marketing, the publishers appealed to us by themselves and asked to tell about our activities, magnetic phase diagram, frustrations, etc. As a matter of fact, we have done everything we wanted on this subject, all findings have been published, so it is time to undertake something new.
Is it clear already what you are going to deal with?
– When selecting the research direction we shall make a start from our own knowledge, skills and interest towards the subject. Of course, it is great luck to find an area where you will be the first to get interesting and important results. It is well-known that a fruitful debut idea is great rarity. I have been in the physical science for 36 years, and I came across only five or six zests like this throughout this period. Frustration is one of them. No doubt that the largest “nuggets” have already been selected in this area. One can certainly continue to rock gravel for gold, but this is not that exciting. You will not get crucially new results already. As a person brought up in strict requirements, I believe that if experimentalists need some details, we certainly need to help them to sort out. However, it does not make sense to my mind to simply increase the number of parameters or to draw multidimensional phase diagrams.

From Nanopaprika blogs.....

Researchers unlock spintronics in graphene

Peter Clarke 4/18/2011 9:17 AM EDT

LONDON – A research team from the University of Manchester has shown that an electric current can magnetize graphene, with potential applications in spintronics.
The research team is led by Professor Andre Geim, who shared the 2010 Nobel Prize for Physics for work on graphene, a form of carbon with high electron mobility.
Spintronics exploits the intrinsic spin of the electron in addition to its electrical charge to develop microelectronic devices
The researchers have found a new way to interconnect spin and charge by applying a relatively weak magnetic field to graphene and they found that this causes a flow of spins in the direction perpendicular to electric current, magnetizing the graphene sheet. The results are reported in Science.
The Manchester researchers have also shown that graphene placed on boron nitride is a suitable material for spintronics because the induced magnetism extends over macroscopic distances from the current path without decay.
The group claims that the discovery offers opportunities for redesigning current spintronics devices and creating new ones such as spin-based transistors.
Professor Geim said: "We offer a new mechanism, thanks to the unique properties of graphene. I imagine that many venues of spintronics can benefit from this finding."
Antonio Castro Neto, a physics professor from Boston, writing in a commentary article that accompanied the Science learned paper, wrote: "Apparently not satisfied with what they have accomplished so far, Geim and his collaborators have now demonstrated another completely unexpected effect that involves quantum mechanics at ambient conditions. This discovery opens a new chapter to the short but rich history of graphene."

Made In IBM Labs: Researchers Unveil Nanotechnology Circuits For Wireless Devices

June 13, 2011

Scientists Build the First Wafer-Scale Graphene Integrated Circuit Smaller than a Pinhead 

Recently, IBM Research scientists announced that they have achieved a milestone in creating a building block for the future of wireless devices. In a paper published yesterday in the magazine Science, IBM researchers announced the first integrated circuit fabricated from wafer-size graphene, and demonstrated a broadband frequency mixer operating at frequencies up to 10 gigahertz (10 billion cycles/second).

Designed for wireless communications, this graphene-based analog integrated circuit could improve today's wireless devices and points to the potential for a new set of appli-cations. At today's conventional frequencies, cell phone and transceiver signals could be improved, potentially allowing phones to work where they can't today while, at much higher frequencies, military and medical personnel could see concealed weapons or conduct medical imaging without the same radiation dangers of X-rays.

Graphene, the thinnest electronic material consisting of a single layer of carbon atoms packed in a honeycomb structure, possesses outstanding electrical, optical, mechanical and thermal properties that could make it less expensive and use less energy inside portable electronics like smart phones.

Despite significant scientific progress in the understanding of this novel material and the demonstration of high-performance graphene-based devices, the challenge of integrat-ing graphene transistors with other components on a single chip had not been realized until now, mostly due to poor adhesion of graphene with metals and oxides and the lack of reliable fabrication schemes to yield reproducible devices and circuits.

This new integrated circuit, consisting of a graphene transistor and a pair of inductors compactly integrated on a silicon carbide (SiC) wafer, overcomes these design hurdles by developing wafer-scale fabrication procedures that maintain the quality of graphene and, at the same time, allow for its integration to other components in a complex cir-cuitry.

"Just a few days before IBM commemorates its 100th anniversary, our scientists have achieved a nanotechnology milestone which continues the company's century-long pur-suit of innovation and technology leadership," said T.C. Chen, vice president, Science and Technology, IBM Research. "This research breakthrough has the potential to in-crease the performance of communication devices that enable people to interact with greater efficiency."

The breakthrough is also a major milestone for the Carbon Electronics for RF Applica-tions (CERA) program, funded by DARPA.

How it Works
In this demonstration, graphene is synthesized by thermal annealing of SiC wafers to form uniform graphene layers on the surface of SiC. The fabrication of graphene circuits involves four layers of metal and two layers of oxide to form top-gated graphene transis-tor, on-chip inductors and interconnects.

The circuit operates as a broadband frequency mixer, which produces output signals with mixed frequencies (sum and difference) of the input signals. Mixers are fundamental components of many electronic communication systems. Frequency mixing up to 10 GHz and excellent thermal stability up to 125°C has been demonstrated with the graphene integrated circuit.

The fabrication scheme developed can also be applied to other types of graphene mate-rials, including chemical vapor deposited (CVD) graphene films synthesized on metal films, and are also compatible with optical lithography for reduced cost and throughput.

Previously, the team has demonstrated standalone graphene transistors with a cut-off frequency as high as 100 GHz and 155 GHz for epitaxial and CVD graphene, for a gate length of 240 and 40 nm, respectively.

IBM and Nanotechnology Leadership
In the company's 100 year history, IBM has invested in scientific research to shape the future of computing. Today's announcement is a demonstration of the results garnered by IBM's world-leading scientists and the company's continual investment in and focus on exploratory research.

Nanotechnology is an enabling technology that is expected to spark advances in various fields. These include advanced functional materials, sensing, tools, healthcare, bio-analytics, water purification, energy technology, and more. IBM scientists apply their nanoscience expertise to problems outside of nanoelectronics and help tackle some of the biggest challenges of our time, such as more efficient use of solar energy, and new ways of purifying or desalinating water.

IBM also recently opened the Binnig and Rohrer Nanotechnology Center - a facility for world-class nanoscale research recently opened on the campus of IBM Research – Zu-rich. The building is the centerpiece of a 10-year strategic partnership in nanoscience between IBM and ETH Zurich, one of Europe's premier technical universities, where sci-entists will research novel nanoscale structures and devices to advance energy and in-formation technologies.

SOURCE: IBM Research