| Identification | More | [Name]
Boron | [CAS]
7440-42-8 | [Synonyms]
B
Bα
Bor
BORON
B KR K1
B KR K2
B KR P1
B AM II
B AM III
B KR KT1
BORON-11
B 005915
B 004500
B 004501
B 005910
NFR&kappa
boron atom
BORONFIBRES
boron fibre
BORON METAL
Boron pieces
B AM I BORON
Boron powder
Boron 99.99%
Receptor
S in HNO3 5%
21 components
Monomer-Boron
Basagran-13C6
Boron solution
Formula
BORON STANDARD
Boron Nanorods
Si in HNO3 4%
FCRLB (Fc
B Target 99.9%
DNA pol &epsilon
Basagran 480-13C6
BORON AA STANDARD
2, DNApol&epsilon
B, DNApol&epsilon
Boron crystalline
BORON METAL POWDER
2, DNA pol&epsilon
BORON ICP STANDARD
B, DNA pol&epsilon
100ppm each of Al
100mg/l each of Al
Boron nanoparticals
100mg/l each of Sb
2, DNA pol &epsilon
B, DNA pol &epsilon
BORON,1000 MICROG/ML
Boron Rod/Φ5mm/99.5%
1000mg/l each of Ag
1000ug/ml each of Ag
BORON POWDER LAB 25 G
Silybin(Mixture A&
BORON POWDER LAB 10 G
Boron Rod/Φ10mm/99.5%
boron for high purity
Trona elemental boron
Boron powder amorphous
Regadenoson impurity B
BORON ICP/DCP STANDARD
Boron10mg/LinH2O,100mL
Boron amorphous, 99.5%
Boron amorphous, 93-96%
Aloin (mixture of A&
BORON STANDARD SOLUTION
BORONPOWDER,CRYSTALLINE
Amorphous element boron
BORON AMORPHOUS POWDER
High Purity Boron powder
BORON PIECES <6CM 99+%
Boron pieces, < 1 mm, 99%
Boron ISO 9001：2015 REACH
Boron powder, ≤50 μm, 99%
Amorphous Elemental Boron
Boron powder, ≤5 μm, 99.5%
BORON, CRYSTALLINE, PIECES
BORON CRYSTALLINE GRADE P1
Boronpowder,amorphous(99+%)
BORON CRYSTALLINE 99.999%
BORON CRYSTALLINE GRADE KT1
Boron, aMorphous, ＜1 Micron
BERYLLIUM 10,000PPM FOR ICP
Boron foil, thick 2 mm, 99%
Boron pieces, <20 mm, 99.5%
BORON, AAS SOLUTION STANDARD
Boron powder , amorphous (B)
BORON SINGLE ELEMENT STANDARD
Boronpowder,amorphous(95-97%)
Boronpowder,crystalline(99.4%)
BORON METALLO-ORGANIC STANDARD
BORON PLASMA EMISSION STANDARD
COBALT SOLUTION ICP 1000 UG/ML
Boron powder , crystalline (B)
BORON, FOR ELECTRONIC PURPOSES
K in 5% HNO3 traceable to NIST
Quality Control - 23 components
boron，amorphous for high purity
BUFFERED PEPTONE WATER 10X200ML
BORON, PLASMA STANDARD SOLUTION
Boronpowder,crystalline(99.99%)
Boron powder, amorphous (93-96%)
Boron, 99%, amorphous, <1 micron
BORON ATOMIC ABSORPTION STANDARD
BORON AA SINGLE ELEMENT STANDARD
(E)-2,4-Dichloro-(1-2H)-1-pentene
Boron powder, crystalline (99.5%)
BORON CRYSTALLINE -60 MESH 99%
ICP Analytical - Solutions A &
Cubic Boron Nitride Nanoparticles
Quality Control Std 1 - Sol A &
Boron powder, amorphous (min. 98%)
Passivated amorphous element boron
BORON ATOMIC SPECTROSCOPY STANDARD
BORON, OIL BASED STANDARD SOLUTION
Boron, powder, amorphous, -325 Mesh
Multicomponent IC Std 2 Sol A &
Perkin Elmer Pure 8 - 24 components
Multicomponent IC Std 1 Sol A &
Standard Solution 1mg/l each of Al
Boron nanopowder, APS 80-100 nm, 99%
Multi-element solution 23 components
Calibration solution - 26 components
BORON SINGLE ELEMENT PLASMA STANDARD
Boron, amorphous powder -325 mesh 90%
Boron >=95% (boron), aMorphous powder
BORON CRYSTALLINE -325 MESH 90-95%
Boron, Powder, Amorphous -325 Mesh 90%
Amorphous Elemental Boron/boron powder
BORON AA/ICP CALIBRATION/CHECK STANDARD
BORON, PRACTICAL GRADE, AMORPHOUSPOWDER
Boron pieces, crystalline, ≤20mm, 99.5%
ICP-MS Memory Check Solution Set (A&
Boron nanopowder, APS: 80-100 nm, 99.9%
BORON ICP STANDARD TRACEABLE TO SRM FROM
BORON POWDER SUBMICRON AMORPHOUS &
Boron pieces, crystalline, 1-30mm, 99.5%
Boron powder, For analysis APS >5 micron
Boron, AAS standard solution, B 1000μg/mL
BORON ATOMIC ABSORPTION STANDARD SOLUTION
BORON POWDER, CRYSTALLINE: 99.5%, -60 MESH
Quality Control Standard 2R - 7 components
ICP Calibration Standard (IV) 23 components
BORON PLASMA EMISSION SPECTROSCOPY STANDARD
Boron, plasma standard solution, B 1000μg/mL
Boron plasma standard solution, B 10000μg/mL
Boron Oil based standard solution, B 1000μg/g
|
Formula
BORON POWDER, CRYSTALLINE, ELEC. GR. 99.9999%
ICP-MS Interference Check Solution Set (A&
Boron Wear Metal @5000 μg/g in 75 cSt Base oil
Boron Wear Metal @1000 μg/g in 75 cSt Base oil
Boron powder, crystalline, -4+40 mesh, 99.999%
Boron, Oil based standard solution, B 5000μg/g
Boron, Reference Standard Solution, 1000ppm ±1%
Boronpowder,amorphous,-325mesh,99%(metalsbasis)
SimpleChIP? Enzymatic Cell Lysis Buffers A &
QCSTD-27 Quality Control Standard 27 components
Standard solution for the determination of boron
Boronpowder,crystalline,-325mesh,98%(metalsbasis)
Boron crystalline, 1 cm, 99.7% trace metals basis
Boron, pieces, crystalline, <1cm, 99.7% metals basis
Boron pieces, crystalline, 20mm (0.8in) & down, 99.5%
MULTI ELEMENT STANDARD SOLUTION FOR ICP 10 components
MISA Standard 5 - Fluoride Soluble Group 15 components
ICP multi-element standard solution VIII 24 components
Boron powder, amorphous, -325 mesh, 90%, Mg nominal 5%
Boron, AAS solution standard, Specpure(R), B 1000μg/ml
B AM I BORON AMORPHOUS GRADE I - A PRODUCT OF H.C. STARCK
Boron, plasma standard solution, Specpure(R), B 1000μg/ml
Boron powder, amorphous, APS <1 micron, 93-96%, Mg 3% max
B AM II BORON AMORPHOUS GRADE II - A PRODUCT OF H.C. STARCK
Boronpieces,crystalline,20mm(0.8in)&down,99.5%(metalsbasis)
Boron, Oil based standard solution, Specpure(R), B 5000μg/g
Boron, Oil based standard solution, Specpure(R), B 1000μg/g
Boron, plasma standard solution, Specpure(R), B 10,000μg/ml
boron atomic absorption standard solution,1 mg/ml b in water
Sulfur-Free Boron Standard: B @ 1000 μg/g in Hydrocarbon Oil
Boron AA Standard@1000 μg/mL in Water, tr Ammonium hydroxide
Boron ICP Standard@1000 μg/mL in Water, tr Ammonium hydroxide
B KR P1 BORON CRYSTALLINE GRADE P1 - A PRODUCT OF H.C. STARCK
B AM III BORON AMORPHOUS GRADE III - A PRODUCT OF H.C. STARCK
B KR K2 BORON CRYSTALLINE GRADE K2 - A PRODUCT OF H.C. STARCK
B KR K1 BORON CRYSTALLINE GRADE K1 - A PRODUCT OF H.C. STARCK
Boron powder, amorphous, APS <5 micron, 94-96%, Mg nominal 1%
Boron ICP Standard@10000 μg/mL in Water, tr Ammonium hydroxide
Boron ICP-MS Standard@100 μg/mL in Water, tr Ammonium hydroxide
B KR KT1 BORON CRYSTALLINE GRADE KT1 - A PRODUCT OF H.C. STARCK
3-Isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one-13C6 2,2-Dioxide
Boron ICP-MS Standard@1000 μg/mL in Water, tr Ammonium hydroxide
Boron sputtering target, diam. x thickness 4 inch × 3 mm, ≥99.9%
Boron ICP-MS Standard@10000 μg/mL in Water, tr Ammonium hydroxide
Perkin Elmer Pure 4 (Quality Control Standard 23) - 23 components
Boron powder, crystalline, -4+40 mesh, 99.999% trace metals basis
3-(1-Methylethyl)-2,1,3-benzothiadiazin-4(3H)-one-13C6 2,2-Dioxide
Boron powder, amorphous & crystalline, -325 mesh, 99% (metals basis)
Boron pieces, crystalline, 1-30MM (0.039-1.2in), 99.4% (Metals basis)
3,4-Dihydro-3-isopropyl-1H-2,1,3-benzothiadiazin-4-one-13C6 2,2-Dioxide
Boron powder, crystalline, -100 mesh, 99.9% trace metals basis, >=95% B-11 | [EINECS(EC#)]
231-151-2 | [Molecular Formula]
BH3 | [MDL Number]
MFCD00134034 | [Molecular Weight]
13.83 | [MOL File]
7440-42-8.mol |
| Chemical Properties | Back Directory | [Description]
Boron was discovered by Sir Humphry Davy and J.L. Gay-Lussac in 1808. It is a trivalent
non-metallic element that occurs abundantly in the evaporite ores borax and ulexite.
Boron is never found as a free element on Earth. Boron appears as charcoal-grey pieces or
black powder or as crystalline; is a very hard, black material with a high melting point; and
exists in many polymorphs. Boron has several forms, and the most common one is amorphous
boron, a dark powder, non-reactive to oxygen, water, acids, and alkalis. It reacts with
metals to form borides. Boron is an essential plant micronutrient. Sodium borate is used
in biochemical and chemical laboratories to make buffers. Boric acid is produced mainly
from borate minerals by the reaction with sulphuric acid. Boric acid is an important compound
used in textile products. The most economically important compound of boron
is sodium tetraborate decahydrate or borax, used for insulating fibreglass and sodium
perborate bleach. Compounds of boron are used in organic synthesis, in the manufacture
of a particular type of glasses, and as wood preservatives. Boron filaments are used for
advanced aerospace structures, due to their high strength and light weight. | [Definition]
Nonmetallic element of atomic number 5; group IIIA
of the periodic table. Aw 10.81. Valence 3. Two
stable isotopes: 11 (approximately 81%) and 10
(approximately 19%).
| [Appearance]
Boron is a yellow or brownish-black powder
and may be either crystalline or amorphous. It does not occur
free in nature and is found in the minerals borax, colemanite,
boronatrocalcite, and boracite. | [Melting point ]
2300°C | [Boiling point ]
2550°C | [bulk density]
200-300kg/m3 | [density ]
2.34 g/mL at 25 °C(lit.)
| [storage temp. ]
Storage temperature: no restrictions. | [solubility ]
H2O: soluble
| [form ]
pieces
| [color ]
Dark gray | [Specific Gravity]
2.34～2.37 | [Stability:]
Stable. Substances to be avoided include strong oxidizing agents and strong acids. May decompose on exposure to air-store under nitrogen. Highly flammable. | [Resistivity]
1.5E12 μΩ-cm, 20 °C | [Water Solubility ]
insoluble H2O [MER06] | [Crystal Structure]
Trigonal (rhombohedral) a = 1017 pm α = 65°12' hR105, R3m, β-B type | [Merck ]
13,1333 | [Exposure limits]
ACGIH: TWA 2 mg/m3; STEL 6 mg/m3 | [InChIKey]
UORVGPXVDQYIDP-UHFFFAOYSA-N | [History]
Boron compounds have been known
for thousands of years, but Boron was not discovered
until 1808 by Sir Humphry Davy and by Gay-Lussac and
Thenard. The element is not found free in nature, but occurs
as orthoboric acid usually in certain volcanic spring waters
and as borates in borax and colemanite. Ulexite, another boron
mineral, is interesting as it is nature’s own version of “fiber
optics.” Important sources of boron are the ores rasorite (kernite)
and tincal (borax ore). Both of these ores are found in the
Mojave Desert. Tincal is the most important source of boron
from the Mojave. Extensive borax deposits are also found in
Turkey. Boron exists naturally as 19.9% 10B isotope and 80.1%
11B isotope. Ten other isotopes of boron are known. High-purity
crystalline boron may be prepared by the vapor phase reduction
of boron trichloride or tribromide with hydrogen on
4-6 The Elements
electrically heated filaments. The impure, or amorphous, boron,
a brownish-black powder, can be obtained by heating the
trioxide with magnesium powder. Boron of 99.9999% purity
has been produced and is available commercially. Elemental
boron has an energy band gap of 1.50 to 1.56 eV, which is higher
than that of either silicon or germanium. It has interesting
optical characteristics, transmitting portions of the infrared,
and is a poor conductor of electricity at room temperature,
but a good conductor at high temperature. Amorphous boron
is used in pyrotechnic flares to provide a distinctive green color,
and in rockets as an igniter. By far the most commercially
important boron compound in terms of dollar sales is Na2B4O7
· 5H2O. This pentahydrate is used in very large quantities in
the manufacture of insulation fiberglass and sodium perborate
bleach. Boric acid is also an important boron compound
with major markets in textile fiberglass and in cellulose insulation
as a flame retardant. Next in order of importance is borax
(Na2B4O7 · 10H2O) which is used principally in laundry products.
Use of borax as a mild antiseptic is minor in terms of dollars
and tons. Boron compounds are also extensively used in
the manufacture of borosilicate glasses. The isotope boron-10
is used as a control for nuclear reactors, as a shield for nuclear
radiation, and in instruments used for detecting neutrons.
Boron nitride has remarkable properties and can be used to
make a material as hard as diamond. The nitride also behaves
like an electrical insulator but conducts heat like a metal. It also
has lubricating properties similar to graphite. The hydrides are
easily oxidized with considerable energy liberation, and have
been studied for use as rocket fuels. Demand is increasing for
boron filaments, a high-strength, lightweight material chiefly
employed for advanced aerospace structures. Boron is similar
to carbon in that it has a capacity to form stable covalently
bonded molecular networks. Carboranes, metalloboranes,
phosphacarboranes, and other families comprise thousands
of compounds. Crystalline boron (99.5%) costs about $6/g.
Amorphous boron (94–96%) costs about $1.50/g. Elemental
boron and the borates are not considered to be toxic, and they
do not require special care in handling. However, some of the
more exotic boron hydrogen compounds are definitely toxic
and do require care. | [CAS DataBase Reference]
7440-42-8(CAS DataBase Reference) | [NIST Chemistry Reference]
Boron(7440-42-8) | [EPA Substance Registry System]
7440-42-8(EPA Substance) |
| Hazard Information | Back Directory | [Chemical Properties]
In 1808, Sir Humphry Davy and J. L. Gay-Lussac discovered boron. It is a trivalent, nonmetallic element that occurs abundantly in the evaporite ores, borax and ulexite. Boron is
never found as a free element on Earth. Boron as a crystalline is a very hard, black material with a high melting point, and exists in many polymorphs. Boron has several forms,
the most common form being amorphous boron, a dark powder, non-reactive to oxygen,
water, acids, and alkalis. It reacts with metals to form borides. Boron is an essential plant
micronutrient. Sodium borate is used in biochemical and chemical laboratories to make
buffers. Boric acid is produced mainly from borate minerals by the reaction with sulfuric
acid. Boric acid is an important compound used in textile products.
Compounds of boron are used in organic synthesis, in the manufacture of special
types of glasses, and as wood preservatives. Boron fi laments are used for advanced
aerospace structures owing to their high strength and light weight. It is used as an
antiseptic for minor burns or cuts and is sometimes used in dressings. Boric acid was
fi rst registered in the United States in 1948 as an insecticide for control of cockroaches,
termites, fi re ants, fl eas, silverfi sh, and many other insects. It acts as a stomach poison affecting the insects’ metabolism, and the dry powder is abrasive to the insects’
exoskeleton. Boric acid is generally considered to be safe for use in household kitchens to control cockroaches and ants. The important use of metallic boron is as boron
fi ber. Borate-containing minerals are mined and processed to produce borates for several industrial uses, i.e., glass and ceramics, soaps and detergents, fi re retardants and
pesticides.
The fi bers are used to reinforce the fuselage of fi ghter aircraft, e.g., the B-1 bomber. The
fi bers are produced by vapor deposition of boron on a tungsten fi lament. Pyrex is a brand
name for glassware, introduced by Corning Incorporated in 1915. Originally, Pyrex was
made from thermal shock-resistant borosilicate glass. The common borate compounds
include boric acid, sodium tetraborates (Borax), and boron oxide | [Uses]
In nuclear chemistry as neutron absorber, in Ignitron rectifiers, in alloys, usually to harden other metals. | [Hazard]
Very toxic; industrial poison; causes
depression of the circulation; persistent vomiting;
diarrhea; shock and coma.
| [Health Hazard]
Boron has been studied extensively for its nutritional importance in animals and humans.
There is a growing body of evidence that boron may be an essential element in animals
and humans. Many nutritionists believe that people would benefi t from more boron and
many popular multivitamins, such as centrum, in the diet. The adverse health effects of
boron on humans is limited. However, ingestion/inhalation causes irritation to the mucous
membrane and boron poisoning.
Short-term exposures to boron in work areas are known to cause irritation of the eye,
the upper respiratory tract, and the naso-pharynx, but the irritation disappears with the
stoppage of further exposure. Ingestion of large amounts of boron (about 30 g of boric acid)over short periods of time is known to affect the stomach, intestines, liver, kidney, and
brain and can eventually lead to death in exposed people. | [Potential Exposure]
Boron is used in metallurgy as a degasifying
agent and is alloyed with aluminum, iron, and steel
to increase hardness. It is also a neutron absorber in nuclear
reactors. Boron is frequently encountered in a variety of
chemical formulations including boric acid, various borate
salts, borax, and boron soil supplements. | [First aid]
If this chemical gets into the eyes, remove any
contact lenses at once and irrigate immediately for at least
15 minutes, occasionally lifting upper and lower lids. Seek
medical attention immediately. If this chemical contacts the
skin, remove contaminated clothing and wash immediately
with soap and water. Seek medical attention immediately.
If this chemical has been inhaled, remove from exposure,
begin rescue breathing (using universal precautions, including
resuscitation mask) if breathing has stopped and CPR if
heart action has stopped. Transfer promptly to a medical
facility. When this chemical has been swallowed, get medical
attention. Give large quantities of water and induce
vomiting. Do not make an unconscious person vomit. | [Shipping]
Boron powder or dust: UN3178 Flammable solid,
inorganic, Hazard Class: 4.1; Labels: 4.1—Flammable solid. | [Incompatibilities]
Boron dust may form explosive mixture
in air. Contact with strong oxidizers may cause explosions.
Violent reaction (possible explosion) with concentrated
nitric acid, hydrogen iodide; silver fluoride. Boron is
incompatible with ammonia, bromine tetrafluoride, cesium
carbide, chlorine, fluorine, interhalogens, iodic acid, lead
dioxide, nitric acid, nitrosyl fluoride, nitrous oxide, potassium
nitrite, rubidium carbide. Reacts exothermically with
metals at high temperature above 900° C. | [Waste Disposal]
Dispose of contents and container
to an approved waste disposal plant. All federal, state,
and local environmental regulations must be observed. | [Physical properties]
Boron has only three electrons in its outer shell, which makes it more metal than nonmetal.Nonmetals have four or more electrons in their valence shell. Even so, boron is somewhatrelated to metalloids and also to nonmetals in period 2.
It is never found in its free, pure form in nature. Although less reactive than the metalswith fewer electrons in their outer orbits, boron is usually compounded with oxygen andsodium, along with water, and in this compound, it is referred to as borax. It is also found asa hard, brittle, dark-brown substance with a metallic luster, as an amorphous powder, or asshiny-black crystals.
Its melting point is 2,079°C, its boiling point is 2,550°C, and its density is 2.37 g/cm3. | [Isotopes]
There are a total of 13 isotopes of boron, two of which are stable. The stableisotope B-10 provides 19.85% of the element’s abundance as found in the Earth’s crust,and the isotope B-11 provides 80.2% of boron’s abundance on Earth. | [Origin of Name]
It is named after the Arabic word bawraq, which means “white borax.” | [Occurrence]
Boron is the 38th most abundant element on Earth. It makes up about 0.001% of theEarth’s crust, or 10 parts per million, which is about the same abundance as lead. It is notfound as a free element in nature but rather in the mineral borax, which is a compound ofhydrated sodium, hydrogen, and water. Borax is found in salty lakes, dry lake-beds, or alkalisoils. Other naturally occurring compounds are either red crystalline or less dense, dark-brownor black powder.
Boron is also found in kernite, colemanite, and ulexite ores, and is mined in many countries,including the western United States. | [Characteristics]
Boron is a semimetal, sometimes classed as a metallic or metalloid or even as a nonmetal.It resembles carbon more closely than aluminum. Although it is extremely hard in its purified form—almost as hard asdiamonds—it is more brittle than diamonds, thus limiting its usefulness. It is an excellentconductor of electricity at high temperatures, but acts as an insulator at lower temperatures. | [Preparation]
Boron may be prepared by several methods, such as chemical reduction of boron compounds, electrolytic reduction in nonaqueous phase, or by thermal decomposition. Many boron compounds including boron oxides, borates, boron halides, borohydrides, and fluoroborates can be reduced to boron by a reactive metal or hydrogen at high temperatures:
B2O3 + 3Ca → 2B + 3CaO
The metal is obtained as a black amorphous product.
2BCl3 + 3H2 → 2B + 6HCl
High purity grade boron may be prepared by such hydrogen reduction at high temperatures using a hot filament.
Electrolytic reduction and thermal decomposition have not yet been applied in large scale commercial methods. Electrolysis of alkali or alkaline earth borates produces boron in low purity. Electrolytic reduction of fused melts of boron trioxide or potassium tetrafluroborate in potassium chloride yield boron in high purity. Also, boron tribromide or boron hydrides may be thermally dissociated by heating at elevated temperatures.
Impurities from boron may be removed by successive recrystallization or volatilization at high temperatures. Removal of certain impurities such as oxygen, nitrogen, hydrogen or carbon from boron are more difficult and involve more complex steps. | [Production Methods]
Commercial boron is produced in several ways. (1) Reduction with metals from the abundant B2O3, using lithium, sodium, potassium, magnesium, beryllium, calcium, or aluminum. The reaction is exothermic. Magnesium is the most effective reductant. With magnesium, a brown powder of approximately 90–95% purity is produced. (2) By reduction with compounds, such as calcium carbide or tungsten carbide, or with hydrogen in an electric arc furnace. The starting boron source may be B2O3 or BCl3. (3) Reduction of gaseous compounds with hydrogen. In an atmosphere of a boron halide, metallic filaments or bars at a surface temperature of about 1200 °C will receive depositions of boron upon admission of hydrogen to the process atmosphere. Although the deposition rate is low, boron of high purity can be obtained because careful control over the purity of the starting ingredients is possible. (4) Thermal decomposition of boron compounds, such as the boranes (very poisonous). Boranes in combination with oxygen or H2O are very reactive. In this process, boron halides, boron sulfide, some borides, boron phosphide, sodium borate and potassium borate also can be decomposed thermally. (5) Electrochemical reduction of boron compounds where the smeltings of metallic fluoroborates or metallic borates are electrolytically decomposed. Boron oxide alkali metal oxide–alkali chloride compounds also can be decomposed in this manner.
Elemental boron has found limited use to date in semiconductor applications, although it does possess current-voltage characteristics that make it suitable for use as an electrical switching device. In a limited way, boron also is used as a dopant (p-type) for p?n junctions in silicon. The principal problem deterring the larger use of boron as a semiconductor is the high-lattice defect concentration in the crystals currently available. | [Production Methods]
Until the late 1990s elemental boron had not found widespread
use in industry, where cost of production was a major
obstacle. Now, there is increasing use as new applications for
the element are developed in material composites and use in
nanotechnology. | [Flammability and Explosibility]
Nonflammable | [reaction suitability]
reagent type: catalyst
core: boron | [Agricultural Uses]
Boron (B) is a non-metal occupying the first period and
Group 13 (formerly, Ⅲ B) of the Periodic Table. Boron is essential for the growth of new
cells. Its concentration in monocots and dicots varies
between 6 to 18 ppm and 20 to 60 ppm, respectively. In
most crops, the concentration of boron in mature leaf
tissue is over 20 ppm.
Boron is one of the seven micronutrients needed by
plants. It exists in soils as a (a) primary rock and mineral,
(b) mass combined in soil organic matter or adsorbed on
colloidal clay and hydrous oxide surfaces, and (c) borate
ion in solution. It occurs as borosilicate to the extent of 20
to 200 ppm in most semi-precious minerals that contain 3
to 4 % boron.
Borosilicate contains varying amounts of iron (Fe),
aluminum (Al), manganese (Mn), calcium (Ca), lithium
(Li) and sodium (Na). As boron is resistant to
weathering, its release from the mineral is slow and,
therefore, it cannot meet the need of prolonged and heavy
cropping.
Though boron is essential for plants, its requirements
and tolerances vary widely from plant to plant. It is
required during (a) active cell division, (b) pollen
germination, flower formation, fruit and root
development, material transportation and cation
absorption, (c) new cell development in meristematic
tissue, (d) synthesis of amino acids and proteins, (e)
nodule formation in legumes, ( f ) translocation of sugars,
(g) polymerization of phenolic compounds, and (h)
regulation of carbohydrate metabolism. Although boron
is required for the growth of agricultural crops, it is not
necessary for algae, diatoms, animals, fungi and microorganisms.
Fruits, vegetables, and field crops may suffer from
boron deficiency. The first visual symptom is cessation
of terminal bud growth, followed by the death of young
leaves. Boron deficiency restricts flowering and fruit
development, and the symptoms are (a) thickened, wilted
or curled leaves, (b) thickened, cracked or water-soaked
condition of petioles and stems, and (c) discoloration,
cracking or rotting of fruits, tubers or roots. The
breakdown of internal root tissues gives rise to darkened
areas, referred to as black or brown heart.
The total boron content in soil varies from region to
region and soil to soil. In Indian soils, for instance, the
total boron content ranges between 4 and 630 mg/kg soil,
while the available boron varies from traces to 68 mg/kg
soil. Irrigation of arid and semi-arid soils with boron-rich
water causes toxicity in plants, which can be reduced
with the addition of organic matter.
Boron is available in soils as an organic fraction and is
released on decomposition to be partly absorbed by plants
and partly lost during leaching. In soil solution, boron is
present as a non-ionized molecule (H3BO3) which is
absorbed by plant roots and distributed with the
transpiration stream. The soil texture, pH and the
moisture affect the movement of boron in soils. Coarsetextured
sandy soils are low in boron and crops in such
soils require additional boron in the form of borax,
whereas crops in fine-structured sandy soils do not
respond to the added boron. Fine-textured soils retain
added boron for longer periods than coarse-textured
soils. Clays retain boron more effectively than sands.
Plant uptake of boron from clayey soils is larger than that
from sandy soils.
The soil pH influences the availability of boron; the
higher the pH, the lower the boron uptake and the greater
the deficiency. Generally, for the same type of crop, the
application rate of a fertilizer containing water-soluble
boron is lesser for coarse soils than for fine-textured
sandy soils. Apple, alfalfa, asparagus, beet, celery,
sunflower are some of the crops requiring high levels of
boron (more than 0.5 ppm), whereas carrots, cotton,
lettuce, peanuts, peach, sweet potato, tobacco and tomato
need only 0.10 to 0.15 ppm of boron. The requirement of
barley, beans, citrus, corn, forage grasses, soybeans and
strawberry is lower than 0.1 ppm of the available soil
boron.
Interaction of boron with nutrients plays a vital role in
the efficiency of the use of boron. For instance, boron is
particularly effective with phosphorus, potassium and
micronutrients, whereas its efficiency suffers with
sodium, calcium and magnesium. For a good crop, it is
essential to have a correct calcium to boron ratio.
Boron compounds that are used to overcome boron
deficiency are borax, boric acid, borosilicate glass or
frits, calcium borate (Colemanite) and magnesium borate
(Boracite). All boron materials used as fertilizers are
stable chemicals and create no storage problem. The
various methods by which boron is applied to plants are
by drilling, broadcasting and spraying.
The presence of boron in a fertilizer has to be clearly
stated on the bag.
Borax (Na2B4O7·10H2O) the most popular boroncontaining
fertilizer. For most crops, 15 to 20 kg
borax/ha is applied at the time of sowing or transplanting.
As boron is readily leached out from the soil and the
initial uptake of the plant is large, it is applied as a fused
glass to reduce its solubility.
Solubor, a commercial product, is a highly
concentrated and completely soluble source of boron
(20 %) like borax. It is preferred to borax and is applied as
spray or dust directly to the foliage of fruit trees,
vegetables and other crops. Colemanite, a naturally
occurring calcium borate (Ca2B6O11·5H2O), is less
soluble and is also superior to borax.
Boron frits or borosilicate glass containing up to 6 %
boron provide boron traces to plants. Borosilicate glass,
due to its slow solubility, makes boron available for a
longer time than borax. The finely ground form is more
effective than the coarse variety.
A dilute solution of boric acid and water is sprayed to
be absorbed by the leaves. | [Industrial uses]
Boron (symbol B) is a metallic element closelyresembling silicon. Boron has a specific gravityof 2.31, a melting point of about 2200°C, anda Knoop hardness of 2700 to 3200, equal to aMohs hardness of about 9.3. At 600°C, boronignites and burns with a brilliant green flame.Minute quantities of boron are used in steelsfor case hardening by the nitriding process toform a boron nitride, and in other steels toincrease hardenability, or depth of hardness. Inthese boron steels, as little as 0.003% is beneficial,forming an iron boride, but with largeramounts the steel becomes brittle and susceptibleto hot-short unless it contains titanium orsome other element to stabilize the carbon . Incast iron, boron inhibits graphitization and alsoserves as a deoxidizer. It is added to iron andsteel in the form of ferroboron.
Boron compounds are employed for fluxesand deoxidizing agents in melting metals, andfor making special glasses. Boron, like siliconand carbon, has an immense capacity for formingcompounds, although it has a differentvalence. The boron atom appears to have a lenticularshape, and two boron atoms can make astrong electromagnetic bond, with the boronacting like carbon but with a double ring. | [Industrial uses]
Boron has the atomic number 5 and the symbol B, and is a so-called metalloid. Boron
compounds have been known for many centuries and especially used in the production of glass. At the beginning of the nineteenth century, it was recognised that boron is an essential micronutrient for
plants. A deficiency of boron can lead to deformation in the vegetable growth such as hollow stems and hearts.
Furthermore, the plant growth is reduced and fertility can be affected. In general, boron deficiency leads to
qualitative and quantitative reduction in the production of the crop. Boron is typically available to plants as
boric acid [B(OH)2] or borate [B(OH)4]-. The exact role of boron in plants is not understood, but there is
evidence that it is involved in pectin cross-linking in primary cell walls, which is essential for normal growth
and development of higher plants. | [storage]
Dust is a flammable solid. Store in a cool, dryplace away from incompatible material, sources of heat andignition. Boron powder may decompose on exposure to airand may have to be stored under a nitrogen blanket. | [Structure and conformation]
The space lattice of Boron belongs to the tetragonal system with lattice constants a=0.873 nm, c=1.013 nm (c=0.503 nm is also reported). The rhombohedron system is also formed. The rhombohedron is stable near the melting point.
Energy gap: Eg=1.0–1.5 eV
Activation energy : 1.39±0.05 eV
Electron mobility: μe=0.9 cm2 /V s (300 K, 1.8×1016 cm-3 )
| [Toxicity evaluation]
Boron is ubiquitous in the earth’s crust, and is found in most
soil types in the range 2–100 ppm, and the average concentration
of soil boron is estimated to be 10–20 ppm. The
primary source of boron is the mineral rasorite, also called
kernite. While large areas of the world are boron deficient, high
concentrations are found in parts of western United States, and
throughout China, Brazil, and Russia. The world’s richest
deposits of boron are located in a geographic region that
stretches from the Mediterranean countries inland to
Kazakhstan. |
| Safety Data | Back Directory | [Hazard Codes ]
Xn,F | [Risk Statements ]
R22:Harmful if swallowed.
R11:Highly Flammable.
R63:Possible risk of harm to the unborn child.
R62:Possible risk of impaired fertility. | [Safety Statements ]
S16:Keep away from sources of ignition-No smoking .
S24/25:Avoid contact with skin and eyes .
S45:In case of accident or if you feel unwell, seek medical advice immediately (show label where possible) .
S36/37/39:Wear suitable protective clothing, gloves and eye/face protection .
S27:Take off immediately all contaminated clothing .
S26:In case of contact with eyes, rinse immediately with plenty of water and seek medical advice . | [RIDADR ]
UN 3178 4.1/PG 2 | [WGK Germany ]
- | [RTECS ]
ED7350000 | [TSCA ]
Yes | [HazardClass ]
4.1 | [PackingGroup ]
III | [HS Code ]
28045000 | [Precautions]
Elemental boron is non-toxic and common boron compounds, such as borates and boric
acid, have low toxicity (approximately similar to table salt with the lethal dose being
2–3 g/kg) and do not require special precautions while handling. Some of the more
exotic boron hydrogen compounds, however, are toxic as well as highly flammable and do
require special care when handling | [Hazardous Substances Data]
7440-42-8(Hazardous Substances Data) |
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