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Описание

Beryllium oxide (BeO) is formed by the ignition of beryllium metal in an oxygen atmosphere. The resulting solid is colourless and insoluble in water.

Физические свойства

In the transmittance and reflectance spectra of BeO, the main peak of the reflectance is located at 730 cm^-1and the small peak is located at 1050 cm^-1.The fundamental frequency of the lattice absorption is υ₀=700±10 cm^-1, according to the reflectance analysis.

Физические свойства

Beryllium oxide (BeO) is a white crystalline oxide. It occurs in nature as the mineral “Bromellite”. Historically, beryllium oxide was called glucina or glucinium oxide. It is an electrical insulator and its thermal conductivity is such that it is higher than any other nonmetal except diamond, and actually exceeds that of some metals. Its high melting point leads to its use as a refractory.

Физические свойства

It is the only material with diamond that combines both excellent thermal shock resistance, high electrical resistivity, and high thermal conductivity, and hence is used for heat sinks in electronics. Beryllia is very soluble in water, but slowly in concentrated acids and alkalis. Highly toxic. Exhibits outstanding corrosion resistance to liquid metals Li, Na, Al, Ga, Pb, Ni, and Ir. Readily attacked by molten metals such as Be, Si, Ti, Zr, Nb, Ta, Mo, and W. Maximum service temperature 2400°C.

Использование

Beryllium oxide is used in the manufacture of high-temperature refractory material and high-quality electrical porcelains, such as aircraft spark plugs and ultrahigh-frequency radar insulators. The high thermal conductivity of beryllium oxide and its good high- frequency electrical insulating properties find application in electrical and electronic fields.
Another use of beryllium oxide is as a slurry for coating graphite crucibles to insulate the graphite and to avoid contamination of melted alloys with carbon. Beryllium oxide crucibles are used where exceptionally high-purity or reactive metals are being melted. In the field of beryllium oxide ceramics, a type of beryllia has been developed that can be formed into custom shapes for electronic and microelectronic circuits. Beryllium oxide has a high thermal conductivity, equal to that of aluminum, and excellent insulating properties, which permits closer packing of semiconductor functions in silicon integrated circuits.

Определение

ChEBI: A beryllium molecular entity consisting of beryllium (+2 oxidation state) and oxide in the ratio 1:1. In the solid state, BeO adopts the hexagonal wurtzite structure form while in the vapour phase, it is present as discrete diatomic covalent molecules.

Подготовка

Beryllium oxide can be prepared by calcining beryllium carbonate, dehydrating the hydroxide or igniting the metal with oxygen gas, as shown in the following reactions:
BeCO₃→BeO＋CO₂
Be(OH)₂→BeO＋H₂O
2Be＋O₂→2BeO
Igniting beryllium in air

Общее описание

Odorless white solid. Sinks in water.

Реакции воздуха и воды

The amount of heat generated by hydrolysis may be large.

Профиль реактивности

BERYLLIUM OXIDE is incompatible with the following: Acids, caustics, chlorinated hydrocarbons, oxidizers, molten lithium, magnesium .

Опасность

Highly toxic by inhalation. Keep container tightly closed and flush out after use.

Угроза здоровью

Any dramatic, unexplained weight loss should be considered as possible first indication of beryllium disease. Other symptoms include anorexia, fatigue, weakness, malaise. Inhalation causes pneumonitis, nasopharyngitis, tracheobronchitis, dyspnea, chronic cough. Contact with dust causes conjunctival inflammation of eyes and irritation of skin.

Пожароопасность

Special Hazards of Combustion Products: Toxic BERYLLIUM OXIDE fume may form in fire.

Промышленное использование

A colorless to white crystalline powder of the composition beryllium oxide, also called beryllia. It has a specific gravity of 3.025, a high melting point, about 2585 C, and a Knoop hardness of 2000. It is used for polishing hard metals and for making hot-pressed ceramic parts. Its high heat resistance and thermal conductivity make it useful for crucibles, and its high dielectric strength makes it suitable for high-frequency insulators. Single-crystal beryllia fibers, or whiskers, have a tensile strength above 6800 MPa.
Beryllium oxide is tapped for nuclear reactor service because of its refractoriness, high thermal conductivity, and ability to moderate (slow down) fast neutrons. The thermal neutrons that result are more efficient in causing fusion of uranium- 235. Nuclear industry uses for beryllia include reflectors and the matrix material for fuel elements. When mixed with suitable nuclear poisons, beryllium oxide may be a new candidate for shielding and control rod assembly applications.

Профиль безопасности

Confirmed carcinogen withexperimental tumorigenic data. Experimental teratogenicdata. Other experimental reproductive effects. Incompatible with (Mg +heat). When heated to decomposition it emits very toxicfumes of BeO.

Структура и конформация

The space lattice of Beryllium oxide belongs to the hexagonal system with lattice constants a=0.2698 nm and c=0.4380 nm.