Boron nitride aerogel is an aerogel made of highly porous boron nitride (BN). It typically consists of a mixture of deformed boron nitride nanotubes and nanosheets. It can have a density as low as 0.6 mg/cm3 and a specific surface area as high as 1050 m2/g, and therefore has potential applications as an absorbent, catalyst support and gas storage medium. BN aerogels are highly hydrophobic and can absorb up to 160 times their mass in oil. They are resistant to oxidation in air at temperatures up to 1200 °C, and hence can be reused after the absorbed oil is burned out by flame. BN aerogels can be prepared by template-assisted chemical vapor deposition at a temperature ~900 °C using borazine as the feed gas. [1] Alternatively it can be produced by ball milling h-BN powder, ultrasonically dispersing it in water, and freeze-drying the dispersion. [2]
Aerogel is a synthetic porous ultralight material derived from a gel, in which the liquid component for the gel has been replaced with a gas. The result is a solid with extremely low density and low thermal conductivity. Nicknames include frozen smoke, solid smoke, solid air, solid cloud, blue smoke owing to its translucent nature and the way light scatters in the material. It feels like fragile expanded polystyrene to the touch. Aerogels can be made from a variety of chemical compounds.
Boron nitride is a heat and chemically resistant refractory compound of boron and nitrogen with the chemical formula BN. It exists in various crystalline forms that are isoelectronic to a similarly structured carbon lattice. The hexagonal form corresponding to graphite is the most stable and soft among BN polymorphs, and is therefore used as a lubricant and an additive to cosmetic products. The cubic variety analogous to diamond is called c-BN; it is softer than diamond, but its thermal and chemical stability is superior. The rare wurtzite BN modification is similar to lonsdaleite and may even be harder than the cubic form.
Boron nitride nanotubes (BNNTs) are a polymorph of boron nitride. They were predicted in 1994 and experimentally discovered in 1995. Structurally they are similar to carbon nanotubes, which are cylinders with sub-micrometer diameters and micrometer lengths, except that carbon atoms are alternately substituted by nitrogen and boron atoms. However, the properties of BN nanotubes are very different: whereas carbon nanotubes can be metallic or semiconducting depending on the rolling direction and radius, a BN nanotube is an electrical insulator with a bandgap of ~5.5 eV, basically independent of tube chirality and morphology. In addition, a layered BN structure is much more thermally and chemically stable than a graphitic carbon structure.
Chemical vapor deposition (CVD) is a deposition method used to produce high quality, high-performance, solid materials, typically under vacuum. The process is often used in the semiconductor industry to produce thin films.
Epitaxy refers to the deposition of a crystalline overlayer on a crystalline substrate.
Tungsten(VI) fluoride, also known as tungsten hexafluoride, is an inorganic compound with the formula WF6. It is a toxic, corrosive, colorless gas, with a density of about 13 g/L (roughly 11 times heavier than air.) It is one of the densest known gases under standard conditions. WF6 is commonly used by the semiconductor industry to form tungsten films, through the process of chemical vapor deposition. This layer serves as a low-resistivity metallic "interconnect". It is one of seventeen known binary hexafluorides.
Titanium diboride (TiB2) is an extremely hard ceramic which has excellent heat conductivity, oxidation stability and resistance to mechanical erosion. TiB2 is also a reasonable electrical conductor, so it can be used as a cathode material in aluminium smelting and can be shaped by electrical discharge machining.
A superhard material is a material with a hardness value exceeding 40 gigapascals (GPa) when measured by the Vickers hardness test. They are highly incompressible solids with high electron density and high bond covalency. As a result of their unique properties, these materials are of great interest in many industrial areas including, but not limited to, abrasives, polishing and cutting tools and wear-resistant and protective coatings.
Ion beam assisted deposition or IBAD or IAD is a materials engineering technique which combines ion implantation with simultaneous sputtering or another physical vapor deposition technique. Besides providing independent control of parameters such as ion energy, temperature and arrival rate of atomic species during deposition, this technique is especially useful to create a gradual transition between the substrate material and the deposited film, and for depositing films with less built-in strain than is possible by other techniques. These two properties can result in films with a much more durable bond to the substrate. Experience has shown that some meta-stable compounds like cubic boron nitride (c-BN), can only be formed in thin films when bombarded with energetic ions during the deposition process.
Silicon nitride is a chemical compound of the elements silicon and nitrogen. Si
3N
4 is the most thermodynamically stable of the silicon nitrides. Hence, Si
3N
4 is the most commercially important of the silicon nitrides and is generally understood as what is being referred to where the term "silicon nitride" is used. It is a white, high-melting-point solid that is relatively chemically inert, being attacked by dilute HF and hot H
2SO
4. It is very hard. It has a high thermal stability.
Physical vapor deposition (PVD) describes a variety of vacuum deposition methods which can be used to produce thin films and coatings. PVD is characterized by a process in which the material goes from a condensed phase to a vapor phase and then back to a thin film condensed phase. The most common PVD processes are sputtering and evaporation. PVD is used in the manufacture of items which require thin films for mechanical, optical, chemical or electronic functions. Examples include semiconductor devices such as thin film solar panels, aluminized PET film for food packaging and balloons, and titanium nitride coated cutting tools for metalworking. Besides PVD tools for fabrication, special smaller tools have been developed.
The nanomesh is a new inorganic nanostructured two-dimensional material, similar to graphene. It was discovered in 2003 at the University of Zurich, Switzerland .
Hybrid physical–chemical vapor deposition (HPCVD) is a thin-film deposition technique, that combines physical vapor deposition (PVD) with chemical vapor deposition (CVD).
Triphosphorus pentanitride is an inorganic compound with the chemical formula P3N5. Containing only phosphorus and nitrogen, this material is classified as a binary nitride. No applications have been developed for this material, which remains a topic of research. It is a white solid, although samples often appear colored owing to impurities.
Graphene foam is a solid, open-cell foam made of single-layer sheets of graphene. It is a candidate substrate for the electrode of lithium-ion batteries.
Tube-based nanostructures are nanostructures made of connected tubes and exhibit nanoscale organization above the molecular level.
2D Materials, sometimes referred to as single layer materials, are crystalline materials consisting of a single layer of atoms. These materials have found use in applications such as photovoltaics, semiconductors, electrodes and water purification.
Boron nitride nanosheet is a two-dimensional crystalline form of the hexagonal boron nitride (h-BN), which has a thickness of one to few atomic layers. It is similar in geometry to its all-carbon analog graphene, but has very different chemical and electronic properties – contrary to the black and highly conducting graphene, BN nanosheets are electrical insulators with a band gap of ~5.9 eV, and therefore appear white in color.
Two dimensional hexagonal boron nitride is a material of comparable structure to graphene with potential applications in e.g. photonics., fuel cells and as a substrate for two-dimensional heterostructures. 2D h-BN is isostructural to graphene, but where graphene is conductive, 2D h-BN is a wide-gap insulator.
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