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Beryllium oxide

Beryllium oxide
Unit cell, ball and stick model of beryllium oxide
BeO sample.jpg
Names
Preferred IUPAC name
Beryllium(II) monoxide
Systematic IUPAC name
Oxoberyllium
Other names
Beryllia, Thermalox, Natural bromellite, Thermalox 995.
Identifiers
3D model (Jmol)
3902801
ChEBI
ChemSpider
ECHA InfoCard 100.013.758
EC Number 215-133-1
MeSH beryllium+oxide
PubChem CID
RTECS number DS4025000
UN number 1566
Properties
BeO
Molar mass 25.01 g·mol−1
Appearance Colourless, vitreous crystals
Odor Odourless
Density 3.01 g cm−3
Melting point 2,507 °C (4,545 °F; 2,780 K)
Boiling point 3,900 °C (7,050 °F; 4,170 K)
0.00002 g/100 mL
Band gap 10.6 eV
Thermal conductivity 330 W K−1 m−1
1.719
Structure
Hexagonal
P63mc
C6v
Tetragonal
Linear
Thermochemistry
25.5 J/mol K
13.73–13.81 J K−1 mol−1
−599 kJ/mol
−582 kJ/mol
Hazards
Safety data sheet See: data page
GHS pictograms The skull-and-crossbones pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The health hazard pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word DANGER
H301, H315, H317, H319, H330, H335, H350, H372
P201, P260, P280, P284, P301+310, P305+351+338
Very Toxic T+
R-phrases R49, R25, R26, R36/37/38, R43, R48/23
S-phrases S53, S45
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 4: Very short exposure could cause death or major residual injury. E.g., VX gas Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Lethal dose or concentration (LD, LC):
LD50 (median dose)
 2062 mg kg−1 (mouse, oral)
US health exposure limits (NIOSH):
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)
REL (Recommended)
 Ca C 0.0005 mg/m3 (as Be)
IDLH (Immediate danger)
 Ca [4 mg/m3 (as Be)]
Related compounds
Other anions
Beryllium telluride
Other cations
Supplementary data page
Refractive index (n),
Dielectric constant (εr), etc.
Thermodynamic
data
 Phase behaviour
solid–liquid–gas
UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YesYN ?)
Infobox references

Beryllium oxide (BeO), also known as beryllia, is an inorganic compound with the formula BeO. This colourless solid is a notable electrical insulator with a higher thermal conductivity than any other non-metal except diamond, and exceeds that of most metals. As an amorphous solid, beryllium oxide is white. Its high melting point leads to its use as a refractory. It occurs in nature as the mineral bromellite. Historically and in materials science, beryllium oxide was called glucina or glucinium oxide. Formation of BeO from beryllium and oxygen releases the highest energy per mass of reactants for any chemical reaction, close to 24 MJ/kg.

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. 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 (both of which it is isoelectronic with). 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. At high temperature the structure transforms to a tetragonal form.


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Wikipedia

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