Boron Nitride - Page 9

Northeastern University scientists were commissioned by DARPA (Defense Advanced Research Projects Agency) and ARL (Army Research Laboratory) to modify graphene to provide thermal sensitivity for use in infrared imaging devices such as night-vision goggles for the military. In a four-year project set out to do just that, they ended up creating an entirely new material spun out of boron, nitrogen, carbon, and oxygen that shows evidence of magnetic, optical, and electrical properties as well as DARPA's sought-after thermal ones.

The potential applications of such a material are varied and range from 20-megapixel arrays for cellphone cameras to photodetectors to atomically thin transistors that when multiplied by the billions could fuel computers. 

Researchers at Michigan Technological University created digital switches by combining graphene and boron nitride nanotubes. The combination of these two materials makes for a workable digital switch, which is the basis for controlling electrons in computers, phones, medical equipment and other electronics. This study is a step forward in making semiconductor-free transistors, bypassing many of the troubles that plague silicon.

The main challenge was fusing the materials together, and the scientists addressed it by maximizing their existing chemical structures and exploiting their mismatched features. The team exfoliated graphene and modified the material's surface with tiny pinholes. Then the researchers could grow the nanotubes up and through the pinholes.

Researchers at Rice University developed a theoretical model that shows how a 3D lattice of boron nitride (also known as "white graphene" as it shares many similar qualities with it, but is not made of carbon atoms) could be deployed as a tunable material to control heat flow in electronic devices. Cooling measures that prevent overheating in electronics are important for developing and sustaining advanced electronic components.

Its 3D structure allows the speculated boron nitride system to conduct heat in any direction as opposed to most circuits, in which heat moves in one direction. The multiple heat directing properties of boron nitride provide excellent opportunities to ‘cool’ down electronic devices. This can be controlled further by building pillars of boron nitride of differing shapes and thickness.

MIT researchers managed to use graphene, deposited on top of a similar 2D material called hexagonal boron nitride (hBN), to couple the properties of the different 2D materials to provide a high degree of control over light waves. They state this has the potential to lead to new kinds of light detection, thermal-management systems, and high-resolution imaging devices. 

Both materials are structurally alike (in that they're both composed of hexagonal arrays of atoms that form 2D sheets), but they react to light differently. These different reactions, though, were found by the researchers to be complementary, and assist in gaining control over the behavior of light. The hybrid material blocks light upon applying a particular voltage to the graphene, while allowing a special kind of emission and propagation, called hyperbolicity, when a different voltage is applied. This means that an extremely thin sheet of material can interact strongly with light, allowing beams to be guided, funneled, and controlled by voltages applied to the sheet. This poses a phenomenon previously unobserved in optical systems. 

Scientists at Columbia University made use of graphene and boron nitride to create a suitable environment in which to study other 2D semiconductors: Two layers of boron nitride are used to keep the environment away from the material under test, while graphene provides electrical connections. 

This method may be suitable for testing all 2D materials. The combination of BN and graphene electrodes cam be compared to a socket into which it is possible to place many other materials and study them in an extremely clean environment to understand their true properties and potential.

The field of plasmonics involves surface plasmons that are generated when photons hit a metal surface, and has been much talked about in regards to revolutionary photonic circuits. Researchers from ICFO (Barcelona), in a collaboration with CIC nanoGUNE (San Sebastian), and CNR/Scuola Normale Superiore (Pisa) and Columbia University (New York) claim to have solved one of the major problem in relation to plasmons - the rapid loss of energy that the plasmons experience, limiting the range over which they could travel.

The researchers found that a graphene-boron nitride system is an excellent host for confined light and suppression of plasmon losses (when graphene is encapsulated in boron nitride, electrons can move ballistically for long distances without scattering, even at room temperature).

The University of Nottingham unveiled its new Molecular Beam Epitaxy (MBE) machine, capable of reaching the high temperatures required to grow graphene and boron nitride layers on an industrial scale. This is the first machine of its kind in the world, and the researchers are hoping it will "unlock the full potential of graphene in electronics and optoelectronics".

Over £2m were invested in the design, purchase and other costs of the machine, by the Engineering and Physical Sciences Research Council, The University of Nottingham and the Leverhulme Trust. Professor Sergei Novikov, the lead scientist in this project, stresses that this is indeed a high risk project, but one that could potentially change paradigms toward growing large-area graphene and boron-nitride sheets by bonding together carbon atoms at high temperatures.

Manchester University's graphene Nobel laureate Sir Andre Geim, together with Leonid Levitov from MIT discovered that electrons in a graphene superlattice move at a controllable angle to applied fields - this is like sailboats that sail diagonally to the wind.

A graphene superlattice is made from a sheet of graphene aligned on top of a sheet of boron nitride. This material behave as a semiconductor (unlike graphene itself which is a superconductor). The researchers found that the electrons in the new material behave as neutrinos that acquired a notable mass. This effect has no known analog in particle physics.

Today there are two main methods to produce graphene. You can synthesize the material, or you can exfoliate it from graphite. Now researchers from Penn State University developed a new way to produce high quality single-layer graphene sheets. They use a method they call intercalation - in which molecules or ions are inserted between graphene sheets in graphite and then these molecules pull out single sheets.

Intercalation was actually used way back in 1841, but it always damaged the sheets because it used strong oxidizing or reducing agents. In this new method, they use a mixture of acids without an oxidizing agent. It was found to work on both graphene and boron nitride. The researchers are now trying to speed up the process to make it scalable.

Researchers from Rice University developed a new chemical process that is used to create a tough, ultra-light foam in any size and shape. The new foam (called GO-0.5BN) is made from two 2D materials: graphene oxide and hexagonal boron nitride (hBN) platelets.

This foam can be used as structural component in applications such as electrodes for supercapacitors and batteries and gas absorption material.