Names | |
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Preferred IUPAC name Beryllium(II) monoxide | |
Systematic IUPAC name Oxoberyllium | |
Other names Beryllia, Thermalox, Bromellite, Thermalox 995. [1] | |
Identifiers | |
3D model (JSmol) | |
3902801 | |
ChEBI | |
ChemSpider | |
ECHA InfoCard | 100.013.758 |
EC Number |
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MeSH | beryllium+oxide |
PubChem CID | |
RTECS number |
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UNII | |
UN number | 1566 |
CompTox Dashboard (EPA) | |
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Properties | |
BeO | |
Molar mass | 25.011 g·mol−1 |
Appearance | Colourless, vitreous crystals |
Odor | Odourless |
Density | 3.01 g/cm3 [2] |
Melting point | 2,578 °C (4,672 °F; 2,851 K) [2] |
Band gap | 10.6 eV [3] |
−11.9·10−6 cm3/mol [4] | |
Thermal conductivity | 210 W/(m·K) [5] |
Refractive index (nD) | n11.7184, n2=1.733 [6] [7] |
Structure [8] | |
Hexagonal, zincite | |
P63mc | |
C6v | |
a = 2.6979 Å, c = 4.3772 Å | |
Formula units (Z) | 2 |
Linear | |
Thermochemistry [9] | |
Heat capacity (C) | 25.6 J/(K·mol) |
Std molar entropy (S⦵298) | 13.77±0.04 J/(K·mol) |
Std enthalpy of formation (ΔfH⦵298) | −609.4±2.5 kJ/mol |
Gibbs free energy (ΔfG⦵) | −580.1 kJ/mol |
Enthalpy of fusion (ΔfH⦵fus) | 86 kJ/mol |
Hazards | |
Occupational safety and health (OHS/OSH): | |
Main hazards | Very toxic, Group 1B carcinogen |
GHS labelling: | |
Danger | |
H301, H315, H317, H319, H330, H335, H350, H372 | |
P201, P260, P280, P284, P301+P310, P305+P351+P338 | |
NFPA 704 (fire diamond) | |
Lethal dose or concentration (LD, LC): | |
LD50 (median dose) | 15 mg/kg (mouse, oral) [10] |
NIOSH (US health exposure limits): | |
PEL (Permissible) | TWA 0.002 mg/m3 C 0.005 mg/m3 (30 minutes), with a maximum peak of 0.025 mg/m3 (as Be) [11] |
REL (Recommended) | Ca C 0.0005 mg/m3 (as Be) [11] |
IDLH (Immediate danger) | Ca [4 mg/m3 (as Be)] [11] |
Related compounds | |
Other anions | Beryllium telluride |
Other cations | |
Supplementary data page | |
Beryllium oxide (data page) | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Beryllium oxide (BeO), also known as beryllia, is an inorganic compound with the formula BeO. This colourless solid is an electrical insulator with a higher thermal conductivity than any other non-metal except diamond, and exceeds that of most metals. [12] As an amorphous solid, beryllium oxide is white. Its high melting point leads to its use as a refractory material. [13] It occurs in nature as the mineral bromellite. Historically and in materials science, beryllium oxide was called glucina or glucinium oxide, owing to its sweet taste.
Beryllium oxide can be prepared by calcining (roasting) beryllium carbonate, dehydrating beryllium hydroxide, or igniting metallic beryllium:
Igniting beryllium in air gives a mixture of BeO and the nitride Be3N2. [12] Unlike the oxides formed by the other Group 2 elements (alkaline earth metals), beryllium oxide is amphoteric rather than basic.
Beryllium oxide formed at high temperatures (>800 °C) is inert, but dissolves easily in hot aqueous ammonium bifluoride (NH4HF2) or a solution of hot concentrated sulfuric acid (H2SO4) and ammonium sulfate ((NH4)2SO4).
BeO crystallizes in the hexagonal wurtzite structure, featuring tetrahedral Be2+ and O2− centres, like lonsdaleite and w-BN (with both of which it is isoelectronic). In contrast, the oxides of the larger group-2 metals, i.e., MgO, CaO, SrO, BaO, crystallize in the cubic rock salt motif with octahedral geometry about the dications and dianions. [12] At high temperature the structure transforms to a tetragonal form. [14]
In the vapour phase, beryllium oxide is present as discrete diatomic molecules. In the language of valence bond theory, these molecules can be described as adopting sp orbital hybridisation on both atoms, featuring one σ bond (between one sp orbital on each atom) and one π bond (between aligned p orbitals on each atom oriented perpendicular to the molecular axis). Molecular orbital theory provides a slightly different picture with no net σ bonding (because the 2s orbitals of the two atoms combine to form a filled sigma bonding orbital and a filled sigma* anti-bonding orbital) and two π bonds formed between both pairs of p orbitals oriented perpendicular to the molecular axis. The sigma orbital formed by the p orbitals aligned along the molecular axis is unfilled. The corresponding ground state is ...(2sσ)2(2sσ*)2(2pπ)4 (as in the isoelectronic C2 molecule), where both bonds can be considered as dative bonds from oxygen towards beryllium. [15]
High-quality crystals may be grown hydrothermally, or otherwise by the Verneuil method. For the most part, beryllium oxide is produced as a white amorphous powder, sintered into larger shapes. Impurities, like carbon, can give rise to a variety of colours to the otherwise colourless host crystals.
Sintered beryllium oxide is a very stable ceramic. [16] Beryllium oxide is used in rocket engines[ citation needed ] and as a transparent protective over-coating on aluminised telescope mirrors. Metal-coated beryllium oxide (BeO) plates are used in the control systems of aircraft drive devices. [17]
Beryllium oxide is used in many high-performance semiconductor parts for applications such as radio equipment because it has 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. [18] It is also employed in heat sinks and spreaders that cool electronic devices, such as CPUs, lasers, and power amplifiers. [19] Some power semiconductor devices have used beryllium oxide ceramic between the silicon chip and the metal mounting base of the package to achieve a lower value of thermal resistance than a similar construction of aluminium oxide. It is also used as a structural ceramic for high-performance microwave devices, vacuum tubes, cavity magnetrons [ citation needed ], and gas lasers. BeO has been proposed as a neutron moderator for naval marine high-temperature gas-cooled reactors (MGCR), as well as NASA's Kilopower nuclear reactor for space applications. [20]
BeO is carcinogenic in powdered form [21] and may cause a chronic allergic-type lung disease berylliosis. Once fired into solid form, it is safe to handle if not subjected to machining that generates dust. Clean breakage releases little dust, but crushing or grinding actions can pose a risk. [22]
Beryllium is a chemical element; it has symbol Be and atomic number 4. It is a steel-gray, hard, strong, lightweight and brittle alkaline earth metal. It is a divalent element that occurs naturally only in combination with other elements to form minerals. Gemstones high in beryllium include beryl and chrysoberyl. It is a relatively rare element in the universe, usually occurring as a product of the spallation of larger atomic nuclei that have collided with cosmic rays. Within the cores of stars, beryllium is depleted as it is fused into heavier elements. Beryllium constitutes about 0.0004 percent by mass of Earth's crust. The world's annual beryllium production of 220 tons is usually manufactured by extraction from the mineral beryl, a difficult process because beryllium bonds strongly to oxygen.
A chemical bond is the association of atoms or ions to form molecules, crystals, and other structures. The bond may result from the electrostatic force between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bonds, or some combination of these effects. Chemical bonds are described as having different strengths: there are "strong bonds" or "primary bonds" such as covalent, ionic and metallic bonds, and "weak bonds" or "secondary bonds" such as dipole–dipole interactions, the London dispersion force, and hydrogen bonding.
Carbon monoxide is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simplest carbon oxide. In coordination complexes, the carbon monoxide ligand is called carbonyl. It is a key ingredient in many processes in industrial chemistry.
A ceramic is any of the various hard, brittle, heat-resistant, and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain, and brick.
Nitrogen is a chemical element; it has symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seventh in total abundance in the Milky Way and the Solar System. At standard temperature and pressure, two atoms of the element bond to form N2, a colourless and odourless diatomic gas. N2 forms about 78% of Earth's atmosphere, making it the most abundant chemical species in air. Because of the volatility of nitrogen compounds, nitrogen is relatively rare in the solid parts of the Earth.
Sintering or frittage is the process of compacting and forming a solid mass of material by pressure or heat without melting it to the point of liquefaction. Sintering happens as part of a manufacturing process used with metals, ceramics, plastics, and other materials. The atoms/molecules in the sintered material diffuse across the boundaries of the particles, fusing the particles together and creating a solid piece.
Zirconium dioxide, sometimes known as zirconia, is a white crystalline oxide of zirconium. Its most naturally occurring form, with a monoclinic crystalline structure, is the mineral baddeleyite. A dopant stabilized cubic structured zirconia, cubic zirconia, is synthesized in various colours for use as a gemstone and a diamond simulant.
Magnesium oxide (MgO), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions held together by ionic bonding. Magnesium hydroxide forms in the presence of water (MgO + H2O → Mg(OH)2), but it can be reversed by heating it to remove moisture.
A period 2 element is one of the chemical elements in the second row of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behavior of the elements as their atomic number increases; a new row is started when chemical behavior begins to repeat, creating columns of elements with similar properties.
Nitrogen dioxide is a chemical compound with the formula NO2. One of several nitrogen oxides, nitrogen dioxide is a reddish-brown gas. It is a paramagnetic, bent molecule with C2v point group symmetry. Industrially, NO2 is an intermediate in the synthesis of nitric acid, millions of tons of which are produced each year, primarily for the production of fertilizers.
In chemistry, catenation is the bonding of atoms of the same element into a series, called a chain. A chain or a ring may be open if its ends are not bonded to each other, or closed if they are bonded in a ring. The words to catenate and catenation reflect the Latin root catena, "chain".
Aluminium nitride (AlN) is a solid nitride of aluminium. It has a high thermal conductivity of up to 321 W/(m·K) and is an electrical insulator. Its wurtzite phase (w-AlN) has a band gap of ~6 eV at room temperature and has a potential application in optoelectronics operating at deep ultraviolet frequencies.
Boron trifluoride is the inorganic compound with the formula BF3. This pungent, colourless, and toxic gas forms white fumes in moist air. It is a useful Lewis acid and a versatile building block for other boron compounds.
Zirconium carbide (ZrC) is an extremely hard refractory ceramic material, commercially used in tool bits for cutting tools. It is usually processed by sintering.
A quadruple bond is a type of chemical bond between two atoms involving eight electrons. This bond is an extension of the more familiar types of covalent bonds: double bonds and triple bonds. Stable quadruple bonds are most common among the transition metals in the middle of the d-block, such as rhenium, tungsten, technetium, molybdenum and chromium. Typically the ligands that support quadruple bonds are π-donors, not π-acceptors. Quadruple bonds are rare as compared to double bonds and triple bonds, but hundreds of compounds with such bonds have been prepared.
Radiation damage is the effect of ionizing radiation on physical objects including non-living structural materials. It can be either detrimental or beneficial for materials.
This glossary of chemistry terms is a list of terms and definitions relevant to chemistry, including chemical laws, diagrams and formulae, laboratory tools, glassware, and equipment. Chemistry is a physical science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions; it features an extensive vocabulary and a significant amount of jargon.
Niobium monoxide is the inorganic compound with the formula NbO. It is a grey solid with metallic conductivity.
Solid is one of the four fundamental states of matter along with liquid, gas, and plasma. The molecules in a solid are closely packed together and contain the least amount of kinetic energy. A solid is characterized by structural rigidity and resistance to a force applied to the surface. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire available volume like a gas. The atoms in a solid are bound to each other, either in a regular geometric lattice, or irregularly. Solids cannot be compressed with little pressure whereas gases can be compressed with little pressure because the molecules in a gas are loosely packed.
Ultra-high-temperature ceramics (UHTCs) are a type of refractory ceramics that can withstand extremely high temperatures without degrading, often above 2,000 °C. They also often have high thermal conductivities and are highly resistant to thermal shock, meaning they can withstand sudden and extreme changes in temperature without cracking or breaking. Chemically, they are usually borides, carbides, nitrides, and oxides of early transition metals.