Chemical thermometers – a breakthrough that cater the need in microelectronics industry

With the massive miniaturisation of electronic components, density of the electronic components has been enhanced significantly along with the flowing of heat which results in overheating of the components. But conventional methods are unable to estimate the temperature in the electronic components due to limitation imposed by size of it.

Researchers have recently devised a solution of the above issue by fabricating a molecular film and using it in an electronic component of a nanometric scale. The film is made by spin crossover molecules, a temperature sensitive molecule, which is extremely stable even after several uses. Due to the bi-stability property of these molecules, these molecules exist into two electronic states with difference physical property and interchange the states by absorbing and loosing energy.

Once deposited in the form of a film on an electronic component, the optical properties of SCO molecules change depending on the temperature, enabling this chemical thermometer to establish a nanometric-scale thermal map of the surface of microelectronic circuits. The devise will soon be sued at industrial scale with improved design.

New material for lithium-ion storage - Graphdiyne

Researchers has devised new two-dimensional carbon based materials – called Graphydiyne.  

Carbon is the anode material in lithium-ion batteries. Its layered structure allows lithium ions to travel in and out of the spaces between layers during battery cycling. Carbon has a highly conductive two-dimensional hexagonal crystal lattice, and they form a stable, porous network for efficient electrolyte penetration. However, the fine-tuning of the structural and electrochemical properties is difficult as these carbon materials are mostly prepared from polymeric carbon matter in a top-down synthesis.

Graphdiyne being a hybrid two-dimensional network made of hexagonal carbon rings bridged by two acetylene units, has been used as a nanoweb membrane for the separation of isotopes. However, its distinct electronic properties and web-like structure also make graphdiyne suitable for electrochemical applications. Changshui Huang from the Chinese Academy of Sciences, Beijing, and colleagues have investigated the lithium-storage capabilities and electrochemical properties of tailor-made, electronically adjusted graphdiyne derivatives.

The scientists synthesized the graphdiyne derivatives in a bottom-up approach by adding precursors on a copper foil, which self-organized to form ordered layered nanostructures with distinct electrochemical and morphological properties.

Among these functional groups, those exerting electron-withdrawing effects reduced the band gap of graphdiyne and increased its conductivity, the authors reported. The cyano group was especially effective and, when used as an anodic material, the cyano-modified graphdiyne demonstrated excellent lithium-storage capacity and was stable for thousands of cycles, as the authors reported.

The authors conclude that modified graphdiyne can be prepared by a bottom-up strategy, which is also best suited to build functional two-dimensional carbon material architectures for batteries, capacitors, and other electrocatalytic devices.

 

Storage solution using silicon in battery with the aid of nanotechnology

Silicon along with carbon nanotubes has been used to develop a nanostructure to make an effective design for battery anodes. CNT is used to strengthen the material and modify the way the silicon interacts with lithium, which has been extensively used in electrical cars and other devices.

Scientists at the U.S. Department of Energy's Pacific Northwest National Laboratory have used a novel way to use silicon. Silicon, used in computer chips is attractive as it can hold 10 times the electrical charge per gram compared to graphite. The trouble is, silicon expands greatly when it encounters lithium, and it is too weak to withstand the pressure of electrode manufacturing.

To tackle these issues, a unique nanostructure that prevents silicon's expansion when it is mixed with carbon. Scientist work, which was recently published in the journal Nature Communications, could inform new electrode material designs for other types of batteries and eventually help increase the energy capacity of the lithium-ion batteries in electric cars, electronic devices, and other equipment.

How they do it!!

A conductive and stable form of carbon, graphite is well suited to packing lithium ions into a battery's anode as it charges. Silicon can take on more lithium than graphite, but it tends to expand about 300 percent in volume, causing the anode to break apart. The researchers created a porous form of silicon by aggregating small silicon particles into microspheres about 8 micrometers in diameter.

The electrode with porous silicon structure exhibits a change in thickness of less than 20 percent while accommodating twice the charge of a typical graphite anode. However, unlike previous versions of porous silicon, the microspheres also exhibited extraordinary mechanical strength, thanks to carbon nanotubes that make the spheres resemble balls of yarn.

The researchers created the structure sequentially, starting by coating the carbon nanotubes with silicon oxide. Next, the nanotubes were put into an emulsion of oil and water. Then they were heated to boiling. The coated carbon nanotubes condense into spheres when the water evaporates. Then aluminum and higher heat is used to convert the silicon oxide into silicon, followed by immersion in water and acid to remove by-products. What emerges from the process is a powder composed of the tiny silicon particles on the surface of carbon nanotubes.

Device fabricated to produce high power high frequency waves

Recently Researchers have succeeded to develop a nanodevice that can run 10 times faster than present transistors. The device enables the generation of high-power terahertz waves which are difficult to produce otherwise. Terahertz (THz) waves fall between microwave and infrared radiation in the electromagnetic spectrum, oscillating at frequencies of between 100 billion and 30 trillion cycles per second. Generation of these waves have immense impact on security and medical imaging, sensing, cancer therapy and high-speed wireless communications due to the ability to carry vast quantities of data. These waves can penetrate paper, clothing, wood and walls. It can detect air pollution.

However, THz waves are not widely used because they are costly and cumbersome to generate. But researchers led by Prof. Elison Matioli, built a nanodevice that can generate extremely high-power THz waves.

The compact, cheaper fully electric nanodevice generates high-intensity waves by producing a voltage from 10 V (or lower) to 100 V in the range of a picosecond. The device consists of two metal plates placed very close together, down to 20 nanometres apart. When potential difference between these two plates is applied, electrons surge towards one of the plates (plasma). Once the voltage reaches a certain threshold, the electrons are emitted almost instantly to the second plate. This rapid movement enabled by such fast switches creates a high-intensity pulse that produces high-frequency waves. When hooked up to antennas, the system can produce and radiate high-power THz waves.

The new nanodevice can create both high-energy and high-frequency pulses, unlike present high frequency semiconductor devices, which can only sustain with a few volts before breaking out. The new device has been proposed to surmount these constraint by  nanoplasma and state-of-the-art nanoscale fabrication techniques