Boron Nitride = BN

CAS Number: 10043-11-5
EC Number: 233-136-6
Chemical formula: BN
Molar mass: 24.82 g/mol

Boron nitride is a thermally and chemically resistant refractory compound of boron and nitrogen with the chemical formula BN.
Boron Nitride 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 (zincblende aka sphalerite structure) variety analogous to diamond is called c-BN; Boron Nitride is softer than diamond, but Boron Nitrides thermal and chemical stability is superior.
The rare wurtzite BN modification is similar to lonsdaleite but slightly softer than the cubic form.

Boron nitride (BN is a synthetic material, which although discovered in the early 19th century was not developed as a commercial material until the latter half of the 20th century.
Boron and nitrogen are neighbours of carbon in the periodic table - in combination boron and nitrogen have the same number of outer shell electrons - the atomic radii of boron and nitrogen are similar to that of carbon.
Boron Nitride is not surprising therefore that boron nitride and carbon exhibit similarity in their crystal structure.
In the same way that carbon exists as graphite and diamond, boron nitride can be synthesised in hexagonal and cubic forms.

The synthesis of hexagonal boron nitride powder is achieved by nitridation or ammonalysis of boric oxide at elevated temperature.
Cubic boron nitride is formed by high pressure, high temperature treatment of hexagonal BN.

Hexagonal boron nitride (h-BN) is the equivalent in structure of graphite.
Like graphite Boron Nitrides plate like microstructure and layered lattice structure give Boron Nitride good lubricating properties.
h-BN is resistant to sintering and is usually formed by hot pressing.

Cubic boron nitride (C-BN) has the same structure as diamond and Boron Nitrides properties mirror those of diamond.
Indeed C-BN is the second hardest material next to diamond.
C-BN was first synthesised in 1957, but Boron Nitride is only in the last 15 years that commercial production of C-BN has developed.

Boron nitride is a non-toxic thermal and chemical refractory compound with high electrical resistance, and is most commonly available in colorless crystal or white powder form.
Boron Nitride is an advanced ceramic material and is often referred to as “white graphene” or “inorganic graphite”.
In this article, Let’s discuss the production, general properties, and uses of boron nitride.

Boron nitride (BN) is a binary chemical compound, consisting of equal numbers of boron and nitrogen atoms.
Boron Nitrides empirical formula is therefore BN.
Boron nitride is isoelectronic with carbon and, like carbon, boron nitrides exists as various polymorphic forms, one of which is analogous to diamond and one analogous to graphite.
The diamond-like polymorph is one of the hardest materials known and the graphite-like polymorph is a useful lubricant.

Boron Nitride (BN) is a popular inorganic compound capable of showing different forms and properties.
Similar to many other inorganic compounds, BN has found an important place in the world of chemistry.
However, the potential of BN was discovered later in history compared to other inorganic compounds such as oxides of boron and iron, chlorides, or ammonia.

This delay could be attributed to the fact that BN is not found in nature and actually obtained in the laboratory environment.
BN was first produced at the beginning of the 18th century.
However, Boron Nitrides commercial use did not start until the 1940s.
Since then, Boron Nitride is widely produced and utilized in different industries.

Boron nitride attracts attention due to Boron Nitrides electronic comparability to the world-famous element carbon.
Much like carbon, BN shares the same number of electrons between neighbouring atoms.
Furthermore, BN takes on similar structural properties to carbon.
A surprising equivalence between different phases of BN and phases of carbon based materials is observed.

BN products can exist in several different phases including amorphous (a-BN), hexagonal (h-BN), turbostratic (t-BN), rhombohedral (r-BN), monoclinic (m-BN), orthorhombic (o-BN), wurtzite (w-BN), and cubic (c-BN) phases.
Amongst the different polymorphic forms of BN hexagonal boron nitride (h-BN) and cubic boron nitride (c-BN) attract the most attention due to their stability, similarity to different phases of carbon based materials, and desirable properties.
Hexagonal boron nitride is often associated with graphite-like carbon based materials while c-BN is often associated with the diamond-like carbon structure.
The first samples of c-BN were produced from hexagonal boron nitride using high pressure and high temperature process in the presence of catalyst in 1957.

After this discovery, much more sophisticated production methods have been developed for the production of c-BN.
But, commercial availability of c-BN was not obtained up until 1969.
Since then, desirable properties of cubic boron nitride have been utilized in several different industries.

Boron nitride (BN) is a binary chemical compound, consisting of equal numbers of boron and nitrogen atoms.
The empirical formula is therefore BN.
Boron nitride is isoelectronic to the elemental forms of carbon and isomorphism occurs between the two species.
That is boron nitride possess three polymorphic forms; one analogous to diamond, one analogous to graphite and ones analogous to the fullerenes.
The diamond-like allotrope of boron nitride is one of the hardest materials known but is softer than materials such as diamond, ultrahard fullerite, and aggregated diamond nanorods.

A hexagonal boron nitride nanosheet (BNNS) is an atomic-thick 2D material that exhibits many interesting properties such as high chemical stability and excellent mechanical and thermal properties.
In Chapter One, the authors introduce two methods for the exfoliation of BNNS from hexagonal boron nitride (hBN).
Then, methodologies for the surface functionalization and nanocomposite construction are demonstrated by two BNNS based nanocomposites.
The catalytic performance of the BNNS based nanocomposites is also evaluated and discussed in detail.

Chapter two evaluates the formation of rolled hexagonal boron nitride nano-sheets (h-BN nanoscrolls) on their unique morphology, magnetic properties and applications.
Due to the high chemical and thermal stabilities, as well as atomically smooth surfaces with free of dangling bonds, hBN has been used as barriers, passivation and support layers in 2D electronic devices, to maximize the electrical and optical characterization of 2D materials.
However, there still remains a challenge in obtaining large-area and high-quality hBN film for real 2D electronic devices.
Chapter Three focuses on chemical vapor deposition (CVD), a promising method to overcome these limitations.

Chapter Four discusses how a boron doped armchair graphene ribbon has been shown by cyclic voltammetry to be a potential catalyst to replace platinum, however the reaction catalyzed was not identified.
The authors use density functional calculations to show the reaction catalyzed is likely dissociation of HO2.
Chapter Five reveals a novel and industrially feasible route to incorporate boron nitride nanoparticles (BNNPs) in radiation-shielding aerospace structural materials.

Chapter Six deals with the preparation and characterization of boron nitride nanotube (BNNT)-reinforced biopolyester matrices.
The morphology, hydrophilicity, biodegradability, cytotoxicity, thermal, mechanical, tribological and antibacterial properties of the resulting nanocomposites are discussed in detail.
Chapter Seven presents theoretical estimations regarding the compressive buckling response of single walled boron nitride nanotubes (SWBNNTs), which have a similar crystal structure as single walled carbon nanotubes (SWCNTs).

Moreover, SWBNNTs have excellent mechanical, insulating and dielectric properties.
Finally, Chapter Eight shows how the different exchange mechanisms can be distinguished and measured by studying solid films where part of the 3He is replaced by immobile Ne atoms.
The authors also show how the formation energy of vacancies and vacancy tunneling frequency can be obtained from NMR studies at high temperature.

Boron Nitride is an advanced synthetic ceramic material available in solid and powder form.
Boron Nitrides unique properties – from high heat capacity and outstanding thermal conductivity to easy machinability, lubricity, low dielectric constant and superior dielectric strength – make boron nitride a truly outstanding material.

In Boron Nitrides solid form, boron nitride is often referred to as “white graphite” because Boron Nitride has a microstructure similar to that of graphite.
However, unlike graphite, boron nitride is an excellent electrical insulator that has a higher oxidation temperature.
Boron Nitride offers high thermal conductivity and good thermal shock resistance and can be easily machined to close tolerances in virtually any shape.
After machining, Boron Nitride is ready for use without additional heat treating or firing operations.

Boron Nitride is a graphite-like, crystalline material that has light-diffusing and texture improving properties.
Boron Nitride is quite the multi-tasker as Boron Nitride can blur imperfections, add an exceptional creamy feel to products and act as a mattifying agent.

In powder makeup products (think blushers, highlighters), Boron Nitride enhances the skin feel and improves the color pay-off.
In lipsticks, Boron Nitride gives a creamy feel and a better color on the lips.

First Aid Measures of Boron Nitride:

General Measures: Remove patient from area of exposure.
Inhalation: Remove to fresh air, keep warm and quiet, give oxygen if breathing is difficult.
Seek medical attention.

Because of excellent thermal and chemical stability, boron nitride ceramics are used in high-temperature equipment and metal casting.
Boron nitride has potential use in nanotechnology.

The empirical formula of boron nitride (BN) is deceptive.
BN is not at all like other diatomic molecules such as carbon monoxide (CO) and hydrogen chloride (HCl).
Rather, Boron Nitride has much in common with carbon, whose representation as the monatomic C is also misleading.

BN, like carbon, has multiple structural forms.
BN’s most stable structure, hBN (shown), is isoelectronic with graphite and has the same hexagonal structure with similar softness and lubricant properties.
hBN can also be produced in graphene-like sheets that can be formed into nanotubes.

In contrast, cubic BN (cBN) is isoelectronic with diamond.
Boron Nitride is not quite as hard, but Boron Nitride is more thermally and chemically stable.
Boron Nitride is also much easier to make.
Unlike diamond, Boron Nitride is insoluble in metals at high temperatures, making Boron Nitride a useful abrasive and oxidation-resistant metal coating.
There is also an amorphous form (aBN), equivalent to amorphous carbon (see below).

BN is primarily a synthetic material, although a naturally occurring deposit has been reported.
Attempts to make pure BN date to the early 20th century, but commercially acceptable forms have been produced only in the past 70 years.
In a 1958 patent to the Carborundum Company (Lewiston, NY), Kenneth M. Taylor prepared molded shapes of BN by heating boric acid (H3BO3) with a metal salt of an oxyacid such as phosphate in the presence of ammonia to form a BN “mix”, which was then compressed into shape.

Today, similar methods are in use that begin with boric trioxide (B2O3) or H3BO3 and use ammonia or urea as the nitrogen source.
All synthetic methods produce a somewhat impure aBN, which is purified and converted to hBN by heating at temperatures higher than used in the synthesis.
Similarly, to the preparation of synthetic diamond, hBN is converted to cBN under high pressure and temperature.

Boron nitride (BN) is a chemical compound that is isoelectronic and isostructural to carbon with equal composition of boron and nitrogen atoms.

Cubical boron nitride (cBN) is the second hardest material known behind diamond.
Boron Nitrides abrasive properties are tremendously relevant for tools in cutting and grinding processes.
In a high pressure/high temperature (HP/HT) process, the rather soft boron nitride (BN) is transformed into the cubic crystal system, where Boron Nitride resembles the structure of diamond (Klocke and König, 2008; Heisel et al., 2014).

After transformation, Boron Nitrides hardness reaches approximately 70 GPa or 3000 HV and a thermal stability up to 2000 °C (Heisel et al., 2014; Uhlmann et al., 2013).
Furthermore, cBN is chemically inert and will not oxidize unless the temperatures exceed 1200 °C.
Currently, the most used cutting materials based on boron nitride can be classified by high cBN-containing and low cBN-containing grades.
High cBN-containing grades consist of 80 to 90% cBN in a metallic W–Co binder phase or ceramic titanium or aluminum based binder phase.

Low cBN-containing grades consist of 45 to 65% cBN and a titanium carbide or titanium nitride based ceramic binder phase (Klocke and König, 2008; Heisel et al., 2014).
Tools containing cBN are preferred for the machining of various materials such as hardened steel, with a hardness of 55 HRC to 68 HRC, sintered metals and cobalt-based superalloys (Klocke and König, 2008).
Compared to diamond, cBN has a significantly lower chemical affinity towards iron or cobalt.
Therefore, Boron Nitride shows higher wear resistance when machining materials consisting of these elements (Marinescu et al., 2006).

boron nitride, (chemical formula BN), synthetically produced crystalline compound of boron and nitrogen, an industrial ceramic material of limited but important application, principally in electrical insulators and cutting tools.
Boron Nitride is made in two crystallographic forms, hexagonal boron nitride (H-BN) and cubic boron nitride (C-BN).

H-BN is prepared by several methods, including the heating of boric oxide (B2O3) with ammonia (NH3).
Boron Nitride is a platy powder consisting, at the molecular level, of sheets of hexagonal rings that slide easily past one another.
This structure, similar to that of the carbon mineral graphite (see the Figure), makes H-BN a soft, lubricious material; unlike graphite, though, H-BN is noted for Boron Nitrides low electric conductivity and high thermal conductivity.
H-BN is frequently molded and then hot-pressed into shapes such as electrical insulators and melting crucibles.
Boron Nitride also can be applied with a liquid binder as a temperature-resistant coating for metallurgical, ceramic, or polymer processing machinery.

C-BN is most often made in the form of small crystals by subjecting H-BN to extremely high pressure (six to nine gigapascals) and temperature (1,500° to 2,000° C, or 2,730° to 3,630° F).
Boron Nitride is second only to diamond in hardness (approaching the maximum of 10 on the Mohs hardness scale) and, like synthetic diamond, is often bonded onto metallic or metallic-ceramic cutting tools for the machining of hard steels.
Owing to Boron Nitrides high oxidation temperature (above 1,900° C, or 3,450° F), Boron Nitride has a much higher working temperature than diamond (which oxidizes above 800° C, or 1,475° F).

Ingestion: Rinse mouth with water.
Do not induce vomiting.
Seek medical attention.
Never induce vomiting or give anything by mouth to an unconscious person.

Skin: Remove contaminated clothing, brush material off skin, wash affected area with soap and water.
Seek medical attention if irritation develops or persists.
Eyes: Flush eyes with lukewarm water, including under upper and lower eyelids, for at least 15 minutes.
Seek medical attention if irritation develops or persists.

Most Important Symptoms/Effects, Acute and Delayed:
May cause irritation.
See section 11 for more information.
Indication of Immediate Medical Attention and Special Treatment:
No other relevant information available.

Firefighting Measures of Boron Nitride:
Extinguishing Media: Use suitable extinguishing agent for surrounding materials and type of fire.
Unsuitable Extinguishing Media: No information available.
Specific Hazards Arising from the Material: May release toxic fumes if involved in a fire.
Special Protective Equipment and Precautions for Firefighters: Wear full face, self-contained breathing apparatus and full protective clothing.

Accidental Relase Measures of Boron Nitride:
Personal Precautions, Protective Equipment, and Emergency Procedures: Wear appropriate respiratory and protective equipment specified.
Isolate spill area and provide ventilation.
Avoid breathing dust or fume.

Avoid contact with skin and eyes.
Methods and Materials for Containment and Cleaning Up: Avoid creating dust.
Scoop or vacuum up spill using a vacuum system equipped with a high efficiency particulate air (HEPA) filtration system and place in a properly labeled closed container for further handling and disposal.
Environmental Precautions: Do not allow to enter drains or to be released to the environment.

Handling And Storages of Boron Nitride:
Precautions for Safe Handling: Avoid creating dust.
Provide adequate ventilation if dusts are created.
Avoid breathing dust or fumes.

Avoid contact with skin and eyes.
Wash thoroughly before eating or smoking.
Conditions for Safe Storage: Store in a cool, dry area.
Store material tightly sealed in properly labeled containers.
Do not store together with oxidizers.

Exposure Controls And Personal Protection of Boron Nitride:
Engineering Controls: Ensure adequate ventilation to maintain exposures below occupational limits.
Whenever possible the use of local exhaust ventilation or other engineering controls is the preferred method of controlling exposure to airborne dust and fume to meet established occupational exposure limits.
Use good housekeeping and sanitation practices.

Do not use tobacco or food in work area.
Wash thoroughly before eating or smoking.
Do not blow dust off clothing or skin with compressed air.

Individual Protection Measures, Such as Personal Protective Equipment:
Respiratory Protection: Use suitable respirator when high concentrations are present.
Eye Protection: Safety glasses
Skin Protection: Impermeable gloves, protective work clothing as necessary.

Material Advantages of Boron Nitride:

To make solid shapes, hBN powders and binders are hot-pressed in billets up to 490mm x 490mm x 410mm at pressures up to 2000 psi and temperatures up to 2000°C.
This process forms a material that is dense and easily machined and ready to use.
Boron Nitride is available in virtually any custom shape that can be machined and has unique characteristics and physical properties which make Boron Nitride valuable for solving tough problems in a wide range of industrial applications.
Excellent thermal shock resistance
High electrical resistivity – excluding aerosols, paints, and ZSBN
Low density

High thermal conductivity
Anisotropic (thermal conductance is different in different planes relative to pressing direction)
Corrosion resistant

Good chemical inertness
High temperature material
Non-wetting

High dielectric breakdown strength, >40 KV/mm
Low dielectric constant, k=4
Excellent machinability

Significance of Boron Nitride in Composites and Its Applications
Boron nitride (BN) exists in several polymorphic forms such as a-BN, h-BN, t-BN, r-BN, m-BN, o-BN, w-BN, and c-BN phases.
Among them, c-BN and h-BN are the most common ceramic powders used in composites to ensure enhanced material properties.
Cubic boron nitride (c-BN) has exceptional properties such as hardness, strength than relating with other ceramics so that are most commonly used as abrasives and in cutting tool applications.

c-BN possesses the second highest thermal conductivity after diamond and relatively low dielectric constant.
Hence pioneer preliminary research in AMCs proven substitute composites than virgin AA 6061 traditionally used for fins in heat sinks.
Moreover, poly-crystalline c-BN (PCBN) tools are most suitable for various machining tasks due to their unmatch-able mechanical properties.
h-BN also finds Boron Nitrides own unique applications where polymer composites for high temperature applications and sp 3 bonding in extreme temperature and compression conditions.

Structure and Chemistry of 2D Materials of Boron Nitride:
BNNSs can also be exfoliated in liquid phase, known as solution processing.
In 2008, Han et al. sonicated h-BN crystals in an organic solution and yielded one- to few-layer single-crystalline BN.
Subsequently, large-scale solution exfoliation of BNNSs was demonstrated using DMF as the solvent.

Liquid exfoliation can also be carried out in water without using any surfactants or organic molecules.
Choosing an appropriate solvent is crucial for exfoliating BNNSs with desired properties.
Production yield, lateral size, and number of layers can be significantly varied depending on the type of solvent used.

In addition, modifying BNNSs with functional groups can affect the interaction between the solvent and bulk BN, enhancing product quality.
Today, solution exfoliation methods are frequently carried out using mixed solvents and electric fields or microwaves to improve controllability.
Liquid exfoliation is an efficient process to prepare large amounts of BNNSs.
However, controlling the number of h-BN layers is very difficult, and sonication usually reduces the size of BNNS flakes.

Discovery of graphene and beyond
Boron nitride (BN), consisting of boron–nitrogen covalent bonds, was commonly used as a refractory material.
Isoelectronic to sp2 carbon lattice, BN was generally compared with carbon allotropes.

The cubic form of BN (c-BN) has a diamond-like crystalline arrangement and the bulk crystal of h-BN is analogous to graphite crystal.
The 2-D sheets of h-BN are the most stable and soft among Boron Nitrides polymorphs, and bonding in h-BN is similar to that in aromatic compounds, but Boron Nitrides considerably less covalency and higher ionic character make Boron Nitride one of the best proton conductors but also an electrical insulator.
Boron Nitrides thermal conductivity is the highest among all electrical insulators (Fig. 1.7).

Atomically thin h-BN sheets, also called “white graphene” can be synthesized by chemical vapor deposition (CVD) of molecular precursors, such as ammonia–borate.
Exfoliation of bulk h-BN under suitable conditions was also demonstrated for large-scale applications in coatings and cosmetics including, but not limited to, lipsticks and lip balms.
h-BN is used as a substrate to grow large-area graphene films because of Boron Nitrides low lattice mismatch with graphene (1.7%).

Nanolayers of h-BN display excellent thermal stability, chemical inertness, and high optical transparency, when compared with those of graphene.
In contrast to electronically conductive graphene, h-BN layers are insulators (band gap ~6 eV) because of the absence of the π-electrons and they show fire-retardant abilities.
The layers of h-BN have unusually high proton conduction rates and when combined with high electrical resistance, these could be useful for fuel cell applications.
Hence, inorganic analogues of graphene, such as h-BN, have paved the way to discover atomic layers of other elements with tunable properties and these include transition metal dichalogenides (TMDs) which are described next.

Porous Materials and Nanomaterials of Boron Nitride:
Boron nitride (BN) ceramics are resistant to chemical attack and molten metals, have high thermal stability in air, and have anisotropic thermal conductivity that are suitable for widespread use in the fabrication of high-temperature crucibles.
BN can exist as multiple phases, and the hexagonal BN (hBN) phase is stable at room temperature.
hBN is the low-density phase that has been widely used as a heat resistant and electrically insulating material.

The hBN phase has a direct bandgap of 5.97 eV and efficiently emits deep UV light.10,42,43 hBN is isostructural to graphite, displaying expected anisotropic mechanical properties, such as facile cleavage and low hardness.
hBN has greater chemical and thermal stabilities than GaN and AlN, which also hold potential as wide-bandgap materials.
BN has two other forms: one isostructural to the cubic zinc blende structure and the other hexagonal and wurtzite-like.
The two forms, referred to as cBN and wBN, are stable at high pressures and temperatures, but can exist at room temperature in a metastable state.

A turbostratic phase, tBN, has also been characterized.
This structure is semicrystalline and lacks ordering in the third dimension, as Boron Nitride is analogous to turbostratic carbon black.
BN offers the lowest density (2.26 g cm−1) among nonoxide ceramics, and introducing porosity into such materials can benefit high-temperature composites and catalyst supports.
Furthermore, BN ceramics hold potential for applications in corrosive environments that are not suited for oxide ceramics.

Porous BN materials, which can be ordered47, or disordered, are most commonly synthesized using hard templates, such as carbon or silica, and advancing porous BN materials requires further development of synthetic techniques.
Fibers, coatings, and foams cannot be prepared from BN powders, as they are with Si3N4 and SiC.
In the past decade, several synthetic avenues have been explored.

Porous BN has been prepared from polymeric precursors as well-crystallized, regularly grained powder.
A mesoporous BN ceramic comprised of hBN crystallites with sizes between 24 and 45 Å has been synthesized using chemical vapor deposition and mesoporous silica as a hard template.
Another mesoporous hBN with low ordering of the porous texture has been synthesized using carbon templating.

A double nanocasting process via a carbonaceous template as a medium starting from zeolite Y (Faujasite) produced an amorphous BN with bimodal micro- and mesoporosity and a surface area of 570 m2 g−1.
The amorphous nature is attributed to the nanometric confinement within the zeolite pores.
This synthetic process involves coupling chemical vapor deposition and polymeric-derived ceramic routes.

In yet another study, mesoporous BN was obtained using a polymerization method in the presence of surfactants.
A method for acquiring mesoporous tBN with interesting cathodoluminescent behavior has been developed.

Many synthetic techniques of BN employ borane-based molecular precursors that are toxic and expensive.
In an effort to avoid these starting materials, amorphous BN was synthesized by placing B2O3 in a graphite crucible, covering with activated carbon, and heating at 1580 °C under a stream of nitrogen.
An intermediate BxCyNz undergoes further heat treatment in air at 600 °C to produce pure BN with a Brunauer–Emmett–Teller (BET) surface area of 167.8 m2 g−1 and an average pore radius of 3.216 nm.

Mesoporous BN can be synthesized by polymerization of a molecular BN precursor, tri(methylamino)borazine (MAB), in a solution of cationic surfactant, cetyl-trimethylammonium bromide (CTAB).
MAB is introduced into a solution of CTAB and then heated at 120 °C to induce polycondensation reactions resulting in a gel.
The solvent is eliminated in vacuo and ceramization is carried out with ammonia at 1000 °C, followed by further thermal treatment.
The resulting BN material has a surface area of 800 m2 g−1 and pores that are 6.0 nm in diameter, with a mesoporosity that is retained up to 1600 °C.
Within the last 10 years, BN with pore diameters ranging from 2.552 to 25 nm51 have been reported.

Abrasives and Abrasive Tools of Boron Nitride:
Boron nitride (B4N) is a crystalline material synthesized from boric anhydride and pure low-ash carbon material in electric furnaces at 1,800°C− 2,500°C (3,300°F–4,500°F).
Boron Nitrides hardness is about 3,800 HV and Boron Nitride has a good cutting ability in the form of loose grains.
However, a low oxidation temperature, of 430°C (800°F), prevents the use of boron nitride for grinding wheels.
Boron Nitride is used exclusively in the form of pastes for sintered carbide lapping, or as grit for sandblasting.

Amorphous form (a-BN) of Boron Nitride:
The amorphous form of boron nitride (a-BN) is non-crystalline, lacking any long-distance regularity in the arrangement of Boron Nitrides atoms.
Boron Nitride is analogous to amorphous carbon.

All other forms of boron nitride are crystalline.

Hexagonal form (h-BN) of Boron Nitride:
The most stable crystalline form is the hexagonal one, also called h-BN, α-BN, g-BN, and graphitic boron nitride.
Hexagonal boron nitride (point group = D6h; space group = P63/mmc) has a layered structure similar to graphite.
Within each layer, boron and nitrogen atoms are bound by strong covalent bonds, whereas the layers are held together by weak van der Waals forces.
The interlayer "registry" of these sheets differs, however, from the pattern seen for graphite, because the atoms are eclipsed, with boron atoms lying over and above nitrogen atoms.

This registry reflects the local polarity of the B–N bonds, as well as interlayer N-donor/B-acceptor characteristics.
Likewise, many metastable forms consisting of differently stacked polytypes exist.
Therefore, h-BN and graphite are very close neighbors, and the material can accommodate carbon as a substituent element to form BNCs.
BC6N hybrids have been synthesized, where carbon substitutes for some B and N atoms.

Cubic form (c-BN) of Boron Nitride:
Cubic boron nitride has a crystal structure analogous to that of diamond.
Consistent with diamond being less stable than graphite, the cubic form is less stable than the hexagonal form, but the conversion rate between the two is negligible at room temperature, as Boron Nitride is for diamond.
The cubic form has the sphalerite crystal structure, the same as that of diamond (with ordered B and N atoms), and is also called β-BN or c-BN.

Wurtzite form (w-BN) of Boron Nitride:
The wurtzite form of boron nitride (w-BN; point group = C6v; space group = P63mc) has the same structure as lonsdaleite, a rare hexagonal polymorph of carbon.
As in the cubic form, the boron and nitrogen atoms are grouped into tetrahedra.

In the wurtzite form, the boron and nitrogen atoms are grouped into 6-membered rings.
In the cubic form all rings are in the chair configuration, whereas in w-BN the rings between 'layers' are in boat configuration.
Earlier optimistic reports predicted that the wurtzite form was very strong, and was estimated by a simulation as potentially having a strength 18% stronger than that of diamond.
Since only small amounts of the mineral exist in nature, this has not yet been experimentally verified.
Recent studies measured w-BN hardness at 46 GPa, slightly harder than commercial borides but softer than the cubic form of boron nitride.

Properties of Boron Nitride:
The substance is composed of hexagonal structures that appear in crystalline form and is usually compared to graphite.
Boron Nitride may come in the form of a flat lattice or a cubic structure, both of which retain the chemical and heat resistance that boron nitride is known for.

Heat and chemical resistance: The compound has a melting point of 2,973°C and a thermal expansion coefficient significantly above that of diamond.
Its hexagonal form resists decomposition even when exposed to 1000°C in ambient air.
Boron nitride doesn’t dissolve in common acids.

Thermal conductivity: At 1700 to 2000 W/mK, boron nitride has a thermal conductivity that is comparable with that of graphene, a similarly hexagon-latticed compound but made up of carbon atoms.
Lubricating property: Boron nitride has the ability to boost the coefficient of friction of lubricating oil, while reducing the potential for wear.
Density: Depending on Boron Nitrides form, Boron Nitrides density ranges from 2.1 to 3.5 g/cm3.

Physical of Boron Nitride:
The partly ionic structure of BN layers in h-BN reduces covalency and electrical conductivity, whereas the interlayer interaction increases resulting in higher hardness of h-BN relative to graphite.
The reduced electron-delocalization in hexagonal-BN is also indicated by Boron Nitrides absence of color and a large band gap.
Very different bonding – strong covalent within the basal planes (planes where boron and nitrogen atoms are covalently bonded) and weak between them – causes high anisotropy of most properties of h-BN.

For example, the hardness, electrical and thermal conductivity are much higher within the planes than perpendicular to them.
On the contrary, the properties of c-BN and w-BN are more homogeneous and isotropic.

Those materials are extremely hard, with the hardness of bulk c-BN being slightly smaller and w-BN even higher than that of diamond.
Polycrystalline c-BN with grain sizes on the order of 10 nm is also reported to have Vickers hardness comparable or higher than diamond.
Because of much better stability to heat and transition metals, c-BN surpasses diamond in mechanical applications, such as machining steel.
The thermal conductivity of BN is among the highest of all electric insulators (see table).

Boron nitride can be doped p-type with beryllium and n-type with boron, sulfur, silicon or if co-doped with carbon and nitrogen.
Both hexagonal and cubic BN are wide-gap semiconductors with a band-gap energy corresponding to the UV region.
If voltage is applied to h-BN or c-BN, then Boron Nitride emits UV light in the range 215–250 nm and therefore can potentially be used as light-emitting diodes (LEDs) or lasers.

Little is known on melting behavior of boron nitride.
Boron Nitride sublimates at 2973 °C at normal pressure releasing nitrogen gas and boron, but melts at elevated pressure.

Thermal stability of Boron Nitride:
Hexagonal and cubic BN (and probably w-BN) show remarkable chemical and thermal stabilities.
For example, h-BN is stable to decomposition at temperatures up to 1000 °C in air, 1400 °C in vacuum, and 2800 °C in an inert atmosphere.

Thermal stability of c-BN can be summarized as follows:
In air or oxygen: B2O3 protective layer prevents further oxidation to ~1300 °C; no conversion to hexagonal form at 1400 °C.
In nitrogen: some conversion to h-BN at 1525 °C after 12 h.
In vacuum (10−5 Pa): conversion to h-BN at 1550–1600 °C.

Chemical stability of Boron Nitride:
Boron nitride is insoluble in the usual acids, but is soluble in alkaline molten salts and nitrides, such as LiOH, KOH, NaOH-Na2CO3, NaNO3, Li3N, Mg3N2, Sr3N2, Ba3N2 or Li3BN2, which are therefore used to etch BN.

Thermal conductivity of Boron Nitride:
The theoretical thermal conductivity of hexagonal boron nitride nanoribbons (BNNRs) can approach 1700–2000 W/(m⋅K), which has the same order of magnitude as the experimental measured value for graphene, and can be comparable to the theoretical calculations for graphene nanoribbons.
Moreover, the thermal transport in the BNNRs is anisotropic.
The thermal conductivity of zigzag-edged BNNRs is about 20% larger than that of armchair-edged nanoribbons at room temperature.

Natural occurrence of Boron Nitride:
In 2009, a naturally occurring boron nitride mineral in the cubic form (c-BN) was reported in Tibet, and the name qingsongite proposed.
The substance was found in dispersed micron-sized inclusions in chromium-rich rocks.
In 2013, the International Mineralogical Association affirmed the mineral and the name.

Properties & Production of Boron Nitride:
Boron nitride (BN) is produced synthetically by the reaction of boric acid or boron oxide and nitrogen in the air.
Boron nitride uses are vast because of Boron Nitrides unique properties, such as good thermal shock resistance, non-toxicity, high thermal conductivity, chemical inertness, etc.
Boron Nitride also has a very high melting point (2,973°C).

BN is a chemical compound with an equal number of boron and nitrogen, possessing different properties than other atomic molecules (carbon dioxide (CO) and hydrogen chloride (HCI)), in that Boron Nitride has much to do with carbon.
And just like carbon, BN exists in crystalline forms, which are Hexagonal boron nitride, cubic boron nitride, and wurtzite boron nitride.
Boron Nitride can be adapted into different shapes (bars, rods, and plates), different forms (powder, solid-liquid, aerosol spray forms), and the grades vary as well (A, AX, 05, HP, M, and M26).

Among all crystalline forms of boron nitride, the most common phases are hexagonal boron nitride (h-BN), which comes in a graphite-like structure, and cubic boron nitride (c-BN), which has a diamond-like structure.
Having established a clear definition of boron nitride, let’s go to the different forms of boron nitride, and their uses.

Synthesis of Boron Nitride:
Preparation and reactivity of hexagonal BN
Boron nitride is produced synthetically.

Hexagonal boron nitride is obtained by the reacting boron trioxide (B2O3) or boric acid (H3BO3) with ammonia (NH3) or urea (CO(NH2)2) in a nitrogen atmosphere:[28]
B2O3 + 2 NH3 → 2 BN + 3 H2O (T = 900 °C)
B(OH)3 + NH3 → BN + 3 H2O (T = 900 °C)
B2O3 + CO(NH2)2 → 2 BN + CO2 + 2 H2O (T > 1000 °C)
B2O3 + 3 CaB6 + 10 N2 → 20 BN + 3 CaO (T > 1500 °C)

The resulting disordered (amorphous) boron nitride contains 92–95% BN and 5–8% B2O3.
The remaining B2O3 can be evaporated in a second step at temperatures > 1500 °C in order to achieve BN concentration >98%.
Such annealing also crystallizes BN, the size of the crystallites increasing with the annealing temperature.

BN parts can be fabricated inexpensively by hot-pressing with subsequent machining.
The parts are made from boron nitride powders adding boron oxide for better compressibility.
Thin films of boron nitride can be obtained by chemical vapor deposition from boron trichloride and nitrogen precursors.
Combustion of boron powder in nitrogen plasma at 5500 °C yields ultrafine boron nitride used for lubricants and toners.

Boron nitride reacts with iodine fluoride in trichlorofluoromethane at −30 °C to produce an extremely sensitive contact explosive, NI3, in low yield.
Boron nitride reacts with nitrides of lithium, alkaline earth metals and lanthanides to form nitridoborate compounds.
For example:
Li3N + BN → Li3BN2

Intercalation of hexagonal BN
Similar to graphite, various molecules, such as NH3 or alkali metals, can be intercalated into hexagonal boron nitride, that is inserted between Boron Nitrides layers.
Both experiment and theory suggest the intercalation is much more difficult for BN than for graphite.

Preparation of cubic BN
Synthesis of c-BN uses same methods as that of diamond: cubic boron nitride is produced by treating hexagonal boron nitride at high pressure and temperature, much as synthetic diamond is produced from graphite.
Direct conversion of hexagonal boron nitride to the cubic form has been observed at pressures between 5 and 18 GPa and temperatures between 1730 and 3230 °C, that is similar parameters as for direct graphite-diamond conversion.
The addition of a small amount of boron oxide can lower the required pressure to 4–7 GPa and temperature to 1500 °C.

As in diamond synthesis, to further reduce the conversion pressures and temperatures, a catalyst is added, such as lithium, potassium, or magnesium, their nitrides, their fluoronitrides, water with ammonium compounds, or hydrazine.
Other industrial synthesis methods, again borrowed from diamond growth, use crystal growth in a temperature gradient, or explosive shock wave.
The shock wave method is used to produce material called heterodiamond, a superhard compound of boron, carbon, and nitrogen.

Low-pressure deposition of thin films of cubic boron nitride is possible.
As in diamond growth, the major problem is to suppress the growth of hexagonal phases (h-BN or graphite, respectively).
Whereas in diamond growth this is achieved by adding hydrogen gas, boron trifluoride is used for c-BN.
Ion beam deposition, plasma-enhanced chemical vapor deposition, pulsed laser deposition, reactive sputtering, and other physical vapor deposition methods are used as well.

Preparation of wurtzite BN
Wurtzite BN can be obtained via static high-pressure or dynamic shock methods.
The limits of Boron Nitrides stability are not well defined.
Both c-BN and w-BN are formed by compressing h-BN, but formation of w-BN occurs at much lower temperatures close to 1700 °C.

Production statistics of Boron Nitride:
Whereas the production and consumption figures for the raw materials used for BN synthesis, namely boric acid and boron trioxide, are well known (see boron), the corresponding numbers for the boron nitride are not listed in statistical reports.
An estimate for the 1999 world production is 300 to 350 metric tons.
The major producers and consumers of BN are located in the United States, Japan, China and Germany.
In 2000, prices varied from about $75–120/kg for standard industrial-quality h-BN and were about up to $200–400/kg for high purity BN grades.

Applications of Boron Nitride:

Boron Nitride Coating
Hexagonal boron nitride suspension has a high thermal conductivity.
Boron Nitride is not impregnated with molten metals and can be applied directly to the surface requiring protection, even if the surface is already hot.
Boron Nitride remains consistent at high temperatures and inert to metals, glass or molten salts.

This system is unique in Boron Nitrides properties, making Boron Nitride an ideal lubricant for hot parts and tools.
Boron Nitride is a release agent and an effective coating for all very hot materials.
Boron nitride remains effective up to 800°C in air and 1950°C in inert gas, making Boron Nitride a very good dry lubricant.
Boron Nitrides amazing features and ease of use have earned Boron Nitride the nickname "white graphite".

Specifications of Boron Nitride Coating:
High-temperature lubricant (1950°C)
High-temperature release agent
Protective coating for metals, ceramics, ceramic fibres and graphites

Facilitates casting of molten metals (aluminium, magnesium, zinc and lead)
Facilitates sliding of press tools at very high temperatures
Aerosol packaging for easy and universal use
Boron nitride (BN) is a semiconductor at high temperatures and an insulation at room temperature.

Usage of Boron Nitride Coating:
Clean the surfaces being coated, removing all splashes from melting or welding work
Shake the aerosol well

Spray about 70 cm from the surface being treated
Move the spray slowly and evenly
Apply in thin layers; if they are too thick the coat may crack
Boron Nitride is advisable to overlay several thin layers, waiting for each one to dry before applying the next

Thermocouple and probe protection
Protection for casting tools
High-temperature lubricant: foundry moulds, gasket wire drawing and more

Electrical insulation
Additive for silicone and resin to improve thermal conductivity
Release agent (metallurgy, metallisation industry, plastic injection moulds and more)

Protective layer for sintering and other applications
Coating to reduce friction and increase chemical inertness
BN 1012 is available as an aerosol or in a plastic bottle (5 and 10 litres)

Electrical insulators
The combination of high dielectric breakdown strength and volume resistivity lead to h-BN being used as an electrical insulator however Boron Nitrides’ tendency to oxidise at high temperatures often restrict Boron Nitrides use to vacuum and inert atmosphere operation.

Crucibles and reaction vessles
Boron Nitrides chemical inertness leads to application as thermocouple protection sheaths, crucibles and linings for reaction vessels though as above oxidation must be avoided.

Moulds and evaporating boats
h-BN is used in bulk form or as a coating for refractory moulds used in glass forming and in superplastic forming of titanium.
Boron Nitride is also used as a constituent in composite materials e.g. TiB2/BN composites for metal evaporation boats, and Si3N4/BN for break rings in continuous casting of steel.

Hot isostatic pressing
Boron Nitrides refractoriness combined with the fact that Boron Nitride is not wetted by molten glass lead to h-BN being used in the production of hot isostatically pressed (HIP’ed) material, most notable ceramics.
In this application preformed parts are coated in h-BN prior to glass encapsulation and HIP’ing.
This protects the part being HIP’ed from actually coming into contact with the glass, which in turn makes Boron Nitride easier to remove after HIP’ing.

Machine cutting tools and abrasives
Cutting tools and abrasive components particularly for use with low carbon ferrous metals have been developed using C-BN.
In this application the tools behave in a similar manner to polycrystalline diamond tools but can be used on iron and low carbon alloys without risk of reaction.

Substrates for electronic devices
C-BN is used for substrates for mounting high density and high power electronic components where the high thermal conductivity achieved allows efficient heat dissipation.

Wear resistant coatings
Due to Boron Nitrides high hardness and excellent wear resistant properties, coatings of C-BN have been developed.

Lubricant of Boron Nitride:
The hexagonal form of boron nitride is used as lubricant for paints, cosmetics, pencil lead, and cement for dental applications.
Boron Nitrides lubricating property occurs even in the absence of gas or water molecules within the compound layers, thereby making Boron Nitride a good component for vacuum systems.
Compared to graphite, BN has significantly better chemical stability and electrical conductivity.

Equipment in high-heat environments
Boron Nitrides exceptional resistance to heat lends the compound to a wide variety of applications involving extremely high temperatures.
Hexagonal boron nitride is being used to improve the lubricating properties of rubber, plastic, alloys, and ceramics.

In the case of plastics, inclusion of a BN component provides lower thermal expansion.
Boron Nitride may also be integrated into semiconductor substrates and microwave oven windows.
Boron nitride is an effective component of reaction vessels and crucibles because of Boron Nitrides thermochemical properties.

Semiconductor industry
With a bandgap ranging from 4.5 to 6.4 eV, boron nitride is an excellent wide-gap semiconductor material.
Boron Nitrides intrinsic thermal and dielectric properties make Boron Nitride a suitable substrate in developing metal-oxide-semiconductor field-effect transistors (MOSFETs) and semiconductors.

Abrasive and cutting implements
Due to the physical properties of cubic boron nitride, this polymorph is used as abrasive material for nickel, iron, and selected alloys in conditions where diamond was not found to be suitable (such as under extreme heat).
Boron Nitrides cubic BN form is incorporated in cutting-tool bits and grinding equipment.

Hexagonal BN
Hexagonal BN (h-BN) is the most widely used polymorph.
Boron Nitride is a good lubricant at both low and high temperatures (up to 900 °C, even in an oxidizing atmosphere).
h-BN lubricant is particularly useful when the electrical conductivity or chemical reactivity of graphite (alternative lubricant) would be problematic.
In internal combustion engines, where graphite could be oxidized and turn into carbon sludge, h-BN with Boron Nitrides superior thermal stability can be added to engine lubricant, however, with all nano-particles suspension, Brownian-motion settlement is a key problem and settlement can clog engine oil filters, which limits solid lubricants application in a combustion engine to only automotive race settings, where engine re-building is a common practice.

Since carbon has appreciable solubility in certain alloys (such as steels), which may lead to degradation of properties, BN is often superior for high temperature and/or high pressure applications.
Another advantage of h-BN over graphite is that Boron Nitrides lubricity does not require water or gas molecules trapped between the layers.
Therefore, h-BN lubricants can be used even in vacuum, e.g. in space applications.
The lubricating properties of fine-grained h-BN are used in cosmetics, paints, dental cements, and pencil leads.

Hexagonal BN was first used in cosmetics around 1940 in Japan.
However, because of Boron Nitrides high price, h-BN was soon abandoned for this application.
Boron Nitrides use was revitalized in the late 1990s with the optimization h-BN production processes, and currently h-BN is used by nearly all leading producers of cosmetic products for foundations, make-up, eye shadows, blushers, kohl pencils, lipsticks and other skincare products.

Because of Boron Nitrides excellent thermal and chemical stability, boron nitride ceramics are traditionally used as parts of high-temperature equipment.
h-BN can be included in ceramics, alloys, resins, plastics, rubbers, and other materials, giving them self-lubricating properties.
Such materials are suitable for construction of e.g. bearings and in steelmaking.

Plastics filled with BN have less thermal expansion as well as higher thermal conductivity and electrical resistivity.
Due to Boron Nitrides excellent dielectric and thermal properties, BN is used in electronics e.g. as a substrate for semiconductors, microwave-transparent windows, as a heat conductive yet electrically insulating filler in thermal pastes, and as a structural material for seals.
Many quantum devices use multilayer h-BN as a substrate material.
Boron Nitride can also be used as a dielectric in resistive random access memories.

Hexagonal BN is used in xerographic process and laser printers as a charge leakage barrier layer of the photo drum.
In the automotive industry, h-BN mixed with a binder (boron oxide) is used for sealing oxygen sensors, which provide feedback for adjusting fuel flow.
The binder utilizes the unique temperature stability and insulating properties of h-BN.

Parts can be made by hot pressing from four commercial grades of h-BN.
Grade HBN contains a boron oxide binder; Boron Nitride is usable up to 550–850 °C in oxidizing atmosphere and up to 1600 °C in vacuum, but due to the boron oxide content is sensitive to water.
Grade HBR uses a calcium borate binder and is usable at 1600 °C.
Grades HBC and HBT contain no binder and can be used up to 3000 °C.

Boron nitride nanosheets (h-BN) can be deposited by catalytic decomposition of borazine at a temperature ~1100 °C in a chemical vapor deposition setup, over areas up to about 10 cm2.
Owing to their hexagonal atomic structure, small lattice mismatch with graphene (~2%), and high uniformity they are used as substrates for graphene-based devices.
BN nanosheets are also excellent proton conductors.
Their high proton transport rate, combined with the high electrical resistance, may lead to applications in fuel cells and water electrolysis.

BN has been used since the mid-2000s as a bullet and bore lubricant in precision target rifle applications as an alternative to molybdenum disulfide coating, commonly referred to as "moly".
Boron Nitride is claimed to increase effective barrel life, increase intervals between bore cleaning, and decrease the deviation in point of impact between clean bore first shots and subsequent shots.

Cubic BN of Boron Nitride:
Cubic boron nitride (CBN or c-BN) is widely used as an abrasive.
Boron Nitrides usefulness arises from Boron Nitrides insolubility in iron, nickel, and related alloys at high temperatures, whereas diamond is soluble in these metals.
Polycrystalline c-BN (PCBN) abrasives are therefore used for machining steel, whereas diamond abrasives are preferred for aluminum alloys, ceramics, and stone.
When in contact with oxygen at high temperatures, BN forms a passivation layer of boron oxide.

Boron nitride binds well with metals, due to formation of interlayers of metal borides or nitrides.
Materials with cubic boron nitride crystals are often used in the tool bits of cutting tools.
For grinding applications, softer binders, e.g. resin, porous ceramics, and soft metals, are used.
Ceramic binders can be used as well.
Commercial products are known under names "Borazon" (by Hyperion Materials & Technologies), and "Elbor" or "Cubonite" (by Russian vendors).

Contrary to diamond, large c-BN pellets can be produced in a simple process (called sintering) of annealing c-BN powders in nitrogen flow at temperatures slightly below the BN decomposition temperature.
This ability of c-BN and h-BN powders to fuse allows cheap production of large BN parts.

Similar to diamond, the combination in c-BN of highest thermal conductivity and electrical resistivity is ideal for heat spreaders.
As cubic boron nitride consists of light atoms and is very robust chemically and mechanically, Boron Nitride is one of the popular materials for X-ray membranes: low mass results in small X-ray absorption, and good mechanical properties allow usage of thin membranes, thus further reducing the absorption.

Amorphous BN of Boron Nitride:
Layers of amorphous boron nitride (a-BN) are used in some semiconductor devices, e.g. MOSFETs.
They can be prepared by chemical decomposition of trichloroborazine with caesium, or by thermal chemical vapor deposition methods.
Thermal CVD can be also used for deposition of h-BN layers, or at high temperatures, c-BN.

Other forms of boron nitride

Atomically thin boron nitride
Hexagonal boron nitride can be exfoliated to mono or few atomic layer sheets.
Due to Boron Nitrides analogous structure to that of graphene, atomically thin boron nitride is sometimes called white graphene.

Mechanical properties of Boron Nitride:
Atomically thin boron nitride is one of the strongest electrically insulating materials.
Monolayer boron nitride has an average Young's modulus of 0.865TPa and fracture strength of 70.5GPa, and in contrast to graphene, whose strength decreases dramatically with increased thickness, few-layer boron nitride sheets have a strength similar to that of monolayer boron nitride.

Thermal conductivity of Boron Nitride:
Atomically thin boron nitride has one of the highest thermal conductivity coefficients (751 W/mK at room temperature) among semiconductors and electrical insulators, and Boron Nitrides thermal conductivity increases with reduced thickness due to less intra-layer coupling.

Thermal stability of Boron Nitride:
The air stability of graphene shows a clear thickness dependence: monolayer graphene is reactive to oxygen at 250 °C, strongly doped at 300 °C, and etched at 450 °C; in contrast, bulk graphite is not oxidized until 800 °C.
Atomically thin boron nitride has much better oxidation resistance than graphene.
Monolayer boron nitride is not oxidized till 700 °C and can sustain up to 850 °C in air; bilayer and trilayer boron nitride nanosheets have slightly higher oxidation starting temperatures.
The excellent thermal stability, high impermeability to gas and liquid, and electrical insulation make atomically thin boron nitride potential coating materials for preventing surface oxidation and corrosion of metals and other two-dimensional (2D) materials, such as black phosphorus.

Better surface adsorption of Boron Nitride:
Atomically thin boron nitride has been found to have better surface adsorption capabilities than bulk hexagonal boron nitride.
According to theoretical and experimental studies, atomically thin boron nitride as an adsorbent experiences conformational changes upon surface adsorption of molecules, increasing adsorption energy and efficiency.
The synergic effect of the atomic thickness, high flexibility, stronger surface adsorption capability, electrical insulation, impermeability, high thermal and chemical stability of BN nanosheets can increase the Raman sensitivity by up to two orders, and in the meantime attain long-term stability and extraordinary reusability not achievable by other materials.

Dielectric properties of Boron Nitride:
Atomically thin hexagonal boron nitride is an excellent dielectric substrate for graphene, molybdenum disulfide (MoS2), and many other 2D material-based electronic and photonic devices.
As shown by electric force microscopy (EFM) studies, the electric field screening in atomically thin boron nitride shows a weak dependence on thickness, which is in line with the smooth decay of electric field inside few-layer boron nitride revealed by the first-principles calculations.

Raman characteristics of Boron Nitride:
Raman spectroscopy has been a useful tool to study a variety of 2D materials, and the Raman signature of high-quality atomically thin boron nitride was first reported by Gorbachev et al. in 2011. and Li et al.
However, the two reported Raman results of monolayer boron nitride did not agree with each other.

Cai et al., therefore, conducted systematic experimental and theoretical studies to reveal the intrinsic Raman spectrum of atomically thin boron nitride.
Boron Nitride reveals that atomically thin boron nitride without interaction with a substrate has a G band frequency similar to that of bulk hexagonal boron nitride, but strain induced by the substrate can cause Raman shifts.
Nevertheless, the Raman intensity of G band of atomically thin boron nitride can be used to estimate layer thickness and sample quality.

Boron nitride nanomesh
Boron nitride nanomesh is a nanostructured two-dimensional material.
Boron Nitride consists of a single BN layer, which forms by self-assembly a highly regular mesh after high-temperature exposure of a clean rhodium or ruthenium surface to borazine under ultra-high vacuum.

The nanomesh looks like an assembly of hexagonal pores.
The distance between two pore centers is 3.2 nm and the pore diameter is ~2 nm.
Other terms for this material are boronitrene or white graphene.

The boron nitride nanomesh is not only stable to decomposition under vacuum, air and some liquids, but also up to temperatures of 800 °C.
In addition, Boron Nitride shows the extraordinary ability to trap molecules and metallic clusters which have similar sizes to the nanomesh pores, forming a well-ordered array.
These characteristics promise interesting applications of the nanomesh in areas like catalysis, surface functionalisation, spintronics, quantum computing and data storage media like hard drives.

Boron nitride nanotubes
Boron nitride tubules were first made in 1989 by Shore and Dolan This work was patented in 1989 and published in 1989 thesis (Dolan) and then 1993 Science.
The 1989 work was also the first preparation of amorphous BN by B-trichloroborazine and cesium metal.

Boron nitride nanotubes were predicted in 1994 and experimentally discovered in 1995.
They can be imagined as a rolled up sheet of h-boron nitride.
Structurally, Boron Nitride is a close analog of the carbon nanotube, namely a long cylinder with diameter of several to hundred nanometers and length of many micrometers, except 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.

Boron nitride aerogel
Boron nitride aerogel is an aerogel made of highly porous BN.
Boron Nitride typically consists of a mixture of deformed BN nanotubes and nanosheets.

Boron Nitride 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 weight 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 using borazine as the feed gas.

Composites containing BN
Addition of boron nitride to silicon nitride ceramics improves the thermal shock resistance of the resulting material.
For the same purpose, BN is added also to silicon nitride-alumina and titanium nitride-alumina ceramics.
Other materials being reinforced with BN include alumina and zirconia, borosilicate glasses, glass ceramics, enamels, and composite ceramics with titanium boride-boron nitride, titanium boride-aluminium nitride-boron nitride, and silicon carbide-boron nitride composition.

Health issues of Boron Nitride:
Boron nitride (along with Si3N4, NbN, and BNC) is reported to show weak fibrogenic activity, and to cause pneumoconiosis when inhaled in particulate form.
The maximum concentration recommended for nitrides of nonmetals is 10 mg/m3 for BN and 4 for AlN or ZrN.

Identifiers of Boron Nitride:
CAS Number: 10043-11-5
ChEBI: CHEBI:50883
ECHA InfoCard: 100.030.111
EC Number: 233-136-6
Gmelin Reference: 216
MeSH: Elbor
RTECS number: ED7800000
UNII: 2U4T60A6YD
CompTox Dashboard (EPA): DTXSID5051498
InChI:
InChI=1S/BN/c1-2
Key: PZNSFCLAULLKQX-UHFFFAOYSA-N
InChI=1S/B2N2/c1-3-2-4-1
Key: AMPXHBZZESCUCE-UHFFFAOYSA-N
InChI=1S/B3N3/c1-4-2-6-3-5-1
Key: WHDCVGLBMWOYDC-UHFFFAOYSA-N
InChI=1/BN/c1-2
Key: PZNSFCLAULLKQX-UHFFFAOYAL
SMILES:
Hexagonal (graphite) structure: [BH-]1=[nH+][B-]2=[nH+][BH-]=[n+]3[BH-]=[nH+][B-]4=[nH+][BH-]=[n+]5[BH-]=[nH+][B-]6=[nH+][BH-]=[n+]1[B-]7=[n+]2[B-]3=[n+]4[B-]5=[n+]67
Sphalerite structure: [NH+]12[B-][NH+]3[B-][NH+]([BH-]14)[BH-]1[N+]5([BH-]38)[B-]26[NH+]2[BH-]([N+]4)[NH+]1[B-][NH+]3[BH-]2[N+][BH-]([NH+]6[BH-]([NH+])[NH+]68)[NH+]([B-]6)[BH-]35
Wurtzite structure: [N+]7[BH-]2[N+][BH-]3[NH+]8[BH-]4[N+][BH-]5[N+][B-]78[N+]90[B-][NH+]5[B-][NH+]4[BH-]9[NH+]3[B-][NH+]2[B-]0

Molecular Weight: 24.82
Appearance: solid
Melting Point: 2527 °C
Boiling Point: N/A
Density: 1.9 to 2.1 g/cm3
True Density: 2.29 g/cm3
Size Range: N/A
Average Particle Size: 10 - 100 nm
Specific Surface Area: 10 – 75 m2/g
Morphology: Cubic or hexagonal
Solubility in H2O: N/A
Crystal Phase / Structure: N/A
Electrical Resistivity: 13 to 15 10x Ω-m
Poisson's Ratio: 0.11
Specific Heat: 840 to 1610 J/kg-K
Thermal Conductivity: 29 to 96 W/m-K
Thermal Expansion: 0.54 to 18 µm/m-K
Young's Modulus: 14 to 60 GPa

Properties of Boron Nitride:
Molecular Weight: .82
Hydrogen Bond Donor Count:
Hydrogen Bond Acceptor Count: 1
Rotatable Bond Count: 0
Exact Mass: 25.0123792
Monoisotopic Mass: 25.0123792
Topological Polar Surface Area: 23.8 Ų
Heavy Atom Count: 2
Formal Charge: 0
Complexity: 10
Isotope Atom Count: 0
Defined Atom Stereocenter Count: 0
Undefined Atom Stereocenter Count: 0
Defined Bond Stereocenter Count: 0
Undefined Bond Stereocenter Count: 0
Covalently-Bonded Unit Count: 1
Compound Is Canonicalized: Yes

Chemical formula: BN
Molar mass: 24.82 g/mol
Appearance: Colorless crystals
Density: 2.1 g/cm3 (h-BN); 3.45 g/cm3 (c-BN)
Melting point: 2,973 °C (5,383 °F; 3,246 K) sublimates (c-BN)
Solubility in water: Insoluble
Electron mobility: 200 cm2/(V·s) (c-BN)
Refractive index (nD): 1.8 (h-BN); 2.1 (c-BN)

Structure of Boron Nitride:
Boron nitride exists in multiple forms that differ in the arrangement of the boron and nitrogen atoms, giving rise to varying bulk properties of the material.

Crystal structure of Boron Nitride:
Hexagonal, sphalerite, wurtzite

Thermochemistry of Boron Nitride:
Heat capacity (C): 19.7 J/(K·mol)
Std molar entropy (So298): 14.8 J/K mol
Std enthalpy offormation (ΔfH⦵298): −254.4 kJ/mol
Gibbs free energy (ΔfG˚): −228.4 kJ/mol

Names of Boron Nitride:

IUPAC name of Boron Nitride:
Boron nitride

Synonyms of Boron Nitride:
Boron nitride
10043-11-5
Elbor
azanylidyneborane
Boron nitride (BN)
Denka boron nitride GP
Boron Nitride Nanotubes
MFCD00011317
BN
Borazon
Elboron
Kubonit
Boron Nitride dispersion
Wurzin
Boron nitride, low binder
Geksanit R
Hexanite R
Boron mononitride
Hexanit R
Super mighty M
Kubonit KR
Hexagonal boron nitride ink
Elbor R
Denka GP
Elbor RM
Sho BN
UHP-Ex
Sho BN HPS
SP 1 (Nitride)
BN 40SHP
KBN-H10
Elbor LO 10B1-100
BZN 550
EINECS 233-136-6
UNII-2U4T60A6YD
Bornitrid
nitrure de bore
nitruro de boro
Nano Boron Nitride
Boron nitride paste
Boron Nitride Nanopowder
Boron Nitride Micropowder
Boron Nitride NanoBarbs?
Boron Nitride Nanoparticles
EC 233-136-6
Hexagonal Boron Nitride Powder
[BN]
2U4T60A6YD
Boron Nitride Sputtering Target
DTXSID5051498
Nano Boron Nitride Nanoparticles
CHEBI:50883
Boron Nitride Powder, 99% Nano
Boron Nitride Nanotubes Properties
Boron Nitride Nanoparticle Dispersion
AKOS015833702
Boron nitride BN GRADE C (H?gan?s)
Boron nitride, Aerosol Refractory Paint
Boron nitride, powder, ~1 mum, 98%
Boron nitride BN GRADE A 01 (H?gan?s)
Boron nitride BN GRADE B 50 (H?gan?s)
Boron nitride BN GRADE F 15 (H?gan?s)
FT-0623177
Y1456
Boron Nitride Nanotubes (B) Bamboo structure
LUBRIFORM? Boron Nitride BN 10 (H?gan?s)
LUBRIFORM? Boron Nitride BN 15 (H?gan?s)
Boron Nitride (hBN) Aerosol Spray (13Oz/369g)
Boron Nitride Nanotubes (C) Cylindrical structure
Q410193
Boron nitride, Refractory Brushable Paint, BN 10%
Boron nitride, Refractory Brushable Paint, BN 31%
J-000130
Boron nitride, nanoplatelet, lateral dimensions Tantalum Molybdenum (Ta-Mo) Alloy Sputtering Targets
Boron Nitride Rod,Diameter (mm), 12.7,Length (mm), 300
Boron Nitride Rod,Diameter (mm), 6.4,Length (mm), 300
Boron nitride, ERM(R) certified Reference Material, powder
Boron Nitride Bar,Length (mm), 300,Width (mm), 12.7,Height (mm), 12.7
Boron Nitride Bar,Length (mm), 300,Width (mm), 6.4,Height (mm), 6.4
Boron Nitride Rectangular Plate,Length (mm), 125,Width (mm), 125,Thick (mm), 12.7
Boron Nitride Rectangular Plate,Length (mm), 125,Width (mm), 125,Thick (mm), 6.4
Boron nitride sputtering target, 76.2mm (3.0in) dia x 3.18mm (0.125in) thick
Boron nitride, nanopowder,
Boron nitride
10043-11-5 [RN]
158535-02-5 [RN]
174847-14-4 [RN]
Borane, nitrilo- [ACD/Index Name]
Boron nitride (B12N12)
Boron nitride (B3N3)
Nitriloboran [German] [ACD/IUPAC Name]
Nitriloborane [ACD/IUPAC Name]
Nitriloborane [French] [ACD/IUPAC Name]
165390-92-1 [RN]
233-136-6 [EINECS]
54824-38-3 [RN]
56939-87-8 [RN]
58799-13-6 [RN]
60569-72-4 [RN]
69495-08-5 [RN]
78666-05-4 [RN]
azanylidyneborane
BN 40SHP
BNNT
Borazon
Bornitrid
Boron mononitride
Boron nitride (BN)
Boron nitride BN GRADE A 01 (Höganäs)
Boron nitride BN GRADE B 50 (Höganäs)
Boron nitride BN GRADE C (Höganäs)
Boron nitride BN GRADE F 15 (Höganäs)
Boron Nitride dispersion
Boron Nitride NanoBarbsâ„¢
Boron Nitride Nanotubes
Boron nitride paste
Boron Nitride Powder, 99% Nano
Boron nitrite
boronnitride
Denka boron nitride GP
Denka GP
Elbor
Elbor LO 10B1-100
Elbor R
Elbor RM
Elboron
Geksanit R
Hexagonal boron nitride ink
Hexanit R
Hexanite R
https://www.ebi.ac.uk/chebi/searchId.do?chebiId=CHEBI:50883
KBN-H10
Kubonit
Kubonit KR
MFCD00011317 [MDL number]
Multiwalled boron nitride nanotubes
nitrure de bore
nitruro de boro
Sho BN
Sho BN HPS
SP 1
SP 1 (Nitride)
Super mighty M
UHP-Ex
Wurzin

MeSH of Boron Nitride:
boron nitride
elbor