CAS 7440-42-8 Boron - Materials / Alfa Chemistry

NAVIGATION

Boron

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Catalog Number

ACM7440428

CAS Number

7440-42-8

Product Name

Boron

Structure

Category

Electronic Materials

Synonyms

Boron, powder, 45 max. part. size (micron), weight 10 g, purity 98.%; Boron crystalline B GRADE K2 (H.C. STARCK); Boron, monofilament, 0.080 mm diameter, length 100 m; CTK0H8670; Boron 11, 11B, plasma standard solution, Specpure, 11B 100g/ml; Boron Glycinate 5% 40M; Boron amorphous B GRADE II (H.C. STARCK); Boron crystalline B GRADE K1 (H.C. STARCK); Boron, plasma standard solution, Specpure(R), B 1000microg/ml, H3BO3 in 1% NH4OH; Boron powder, crystalline, elec. gr.;

IUPAC Name

boron;

Molecular Weight

10.81g/mol

Molecular Formula

Canonical SMILES

[B];

InChI

InChI=1S/B;

InChI Key

ZOXJGFHDIHLPTG-UHFFFAOYSA-N;

Melting Point

2,075 deg C;

Density

Amorphous, 2.350 g/cu cm; alpha-rhombohedral, 2.46 g/cu cm; alpha-tetragonal, 2.31 g/cu cm; beta-rhombohedral, 2.35 g/cu cm;

Solubility

Insoluble in water; unaffected by aqueous hydrochloric and hydrofluoric acids; when finely divided it is soluble in boiling nitric and sulfuric acids and in molten metals such as copper, iron, magnesium, aluminum, calcium; reacts vigorously with fused sodium peroxide or with a fusion mixture of sodium carbonate or potassium nitrate;Soluble in concentrated nitric and sulfuric acids; insoluble in water, alcohol, ether;

Application

Boron has found many uses and has become an important industrial chemical. Boron is used as an alloy metal, and when combined with other metals, it imparts exceptional strength to those metals at high temperatures. It is an excellent neutron absorber used to capture neutrons in nuclear reactors to prevent a runaway fission reaction. As the boron rods are lowered into the reactor, they control the rate of fission by absorbing excess neutrons. Boron is also used as an oxygen absorber in the production of copper and other metals, Boron finds uses in the cosmetics industry (talc powder), in soaps and adhesives, and as an environmentally safe insecticide. A small amount of boron is added as a dope to silicon transistor chips to facilitate or impede the flow of current over the chip. Boron has just three valence electrons; silicon atoms have four. This dearth of one electron in boron s outer shell allows it to act as a positive hole in the silicon chip that can be filled or left vacant, thus acting as a type of switch in transistors. Many of today s electronic devices depend on these types of doped-silicon semiconductors and transistors. Boron is also used to manufacture borosilicate glass and to form enamels that provide a protective coating for steel. It is also used as medication for relief of the symptoms of arthritis. Due to boron s unique structure and chemical properties, there are still more unusual compounds to be explored.

Storage

Storage temperature: no restrictions.

Color/Form

Polymorphic: alpha-rhombohedral form, clear red crystals; beta-rhombohedral form, black; alpha-tetragonal form, black, opaque crystals with metallic luster; amorphous form, black or dark brown powder; other crystal forms are known but not entirely characterized;Filaments, powder, whiskers, single crystals;

Covalently-Bonded Unit Count

EC Number

231-151-2

Exact Mass

11.009g/mol

Heavy Atom Count

Monoisotopic Mass

11.009g/mol

Other Experimental

Atomic number 5; naturally-occurring isotopes: 10,11; three short-lived artificial isotopes: 8,12, 13;Alpha-rhombohedral form, 12 atoms/unit cell; beta-rhombohedral form, 105 atoms/unit cell; alpha-tetragonal form, 50 atoms/unit cell;The alpha-rhombohedral form of boron is the simplest crystal structure with slightly deformed cubic close packing, which degrades at 1200 deg C and at 1500 it converts to beta-rhombohedral boron, which is the most thermodynamically stable form.;Crystalline boron is very inert. Low purity, higher temperature, and changes in or lack of crystallinity all increase the chemical reactivity.;Boron exists naturally as (10)B (19.9%) and (11)B (80.1%); ten other isotopes of boron are known;Amorphous form, heat capacity: 2.858 cal/g-atom/deg C at 25 deg C; beta-rhombohedral form, heat capacity: 2.650 cal/g-atom/deg C at 25 deg C;Feeble conductor of electricity at room temperature, good conductor at high temperature; self limiting reaction with oxygen due to formation of boric oxide film; oxide coating evaporates above 1000 deg C; crystals are almost as hard as diamond; reacts with fluorine at room temperature;Energy band gap of 1.50-1.56 eV; transmits portions of the infrared;High neutron absorption capacity; amphoteric; Mohs hardness, 9.3;

Stability

Fairly stable at normal temperature.;

Topological Polar Surface Area

0A^2

UNII

N9E3X5056Q

Vapor Pressure

1.56X10-5 atm (0.0119 mm Hg) at 2140 deg C;

MSDS

Download MSDS

COA

Download COA

Spec Sheet

Download Spec Sheet

Case Study

Synthesis of Boron Nitride Nanotubes from Boron Powder by Ball Milling

Kim, Jun Hee, et al. Nano convergence, 2018, 5(1), 1-13.

Boron and nitrogen atoms are arranged in a hexagonal network in boron nitride nanotubes (BNNTs). Ball milling is an efficient way to synthesize BNNTs from boron powder on a low-cost industrial scale. This method stimulates the direct reaction of boron and nitrogen under ambient conditions by introducing defects or amorphous structures into the boron starting powder.
Synthetic strategies from boron powder to BNNTs
· Boron powder is ball milled in NH3 gas for 150 hours and then isothermally annealed in N2 atmosphere at 1000-1200 °C. Long grinding times can promote the nitration process between boron and NH3, leading to the formation of increased nucleation structures, thus promoting the formation of BNNTs.
· In addition, the growth of BNNTs can also be achieved by catalyzing the surface coating of amorphous boron on iron particles. The crystalline boron powder transforms into an amorphous structure covering the surface iron particles, which then initiates the growth of BNNTs during the annealing stage.

Improving Boron Powder Combustion by Introducing Various Additives

Ma, Kang, et al. Thermochimica Acta, 2022, 718, 179368.

Boron (B) powder has very high energy density and is commonly used as an additive to solid propellants. However, due to its high melting point and the existence of surface oxide film, boron powder is difficult to ignite and burns incompletely. A variety of additives have been studied to modify the combustion characteristics of boron powder, such as metal powders, nickel (Ni) nanoparticles, glycidyl azide polymer (GAP), and ammonium perchlorate (AP).
Modification strategies for boron powder
· Metal powders such as iron (Fe), titanium (Ti) and magnesium (Mg) can be used as effective additives and can also improve the ignition and combustion of B powder. For example, Mg has a low ignition temperature and can react with B2O3 at high temperatures to accelerate the ignition of B powder, thereby increasing the combustion temperature.
· Introducing Ni nanoparticles into boron powder can improve the ignition and combustion of boron powder by forming nickel-modified boron-based complexes (B/Ni). In addition, nickel nanoparticles can also change the reaction path of B through selective oxidation and promote the oxidation reaction of B.
· GAP and AP additives can release a large amount of heat during the combustion process, heating and evaporating the B2O3 film covered on the boron surface, thereby improving the ignition and combustion performance of boron particles.

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