BERYLLIUM OXIDE

Description

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

Physical properties

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.

Physical properties

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.

Physical properties

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.

The Uses of BERYLLIUM OXIDE

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.

The Uses of BERYLLIUM OXIDE

Beryllium oxide is used in many high-performance semiconductor parts for applications such as radio equipment because of its good thermal conductivity while also being a good electrical insulator. It is used as a filler in some thermal interface materials such as “THERMAL GREASE”.Some high-powered semiconductor devices have used beryllium oxide ceramic between the silicon chip and the metal mounting base of the package in order to achieve a higher degree of thermal conductivity than for a similar construction made with Al2O3. It is also used as a structural ceramic for high-performance microwave devices, vacuum tubes, magnetrons and gas lasers. Beryllium oxide (BeO) is a space age technical ceramic material that offers a combination of desirable properties not found in any other material.

The Uses of BERYLLIUM OXIDE

Beryllium oxide?is widely used in industry due to its low density and high thermal and electrical conductivity. It is used in high-technology ceramics, electronic heat sinks, electrical insulators, high-power devices, high-density electrical circuits, microwaves, X-ray windows, nuclear reactor fuels and for various aerospace and military applications.

Definition

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.

Preparation

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

Production Methods

Single crystals are grown by hydrothermal synthesis using Beryllium oxide and NaOH solution, but the size smaller than 0.6 mm is only obtained. The pressed plate (thickness of 0.3–1.0 mm) has the density of 99.5% of a single crystal and has the transmittance almost same as the single crystal.

General Description

Odorless white solid. Sinks in water.

Air & Water Reactions

The amount of heat generated by hydrolysis may be large.

Reactivity Profile

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

Hazard

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

Health Hazard

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.

Fire Hazard

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

Industrial uses

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.

Safety Profile

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.

Structure and conformation

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