Beryllium oxide
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| Beryllium oxide | |
|---|---|
| General | |
| Other names | Beryllia |
| Molecular formula | BeO |
| Molar mass | 25.01 g/mol |
| Appearance | white solid |
| CAS number | [1304-56-9] |
| Properties | |
| Density and phase | 3.0 g/cm3, solid |
| Solubility in water | insoluble |
| Melting point | 2530 °C |
| Boiling point | 3900 °C |
| Structure | |
| Coordination geometry |
? |
| Crystal structure | ? |
| Thermodynamic data | |
| Std enthalpy of formation ΔfH |
−609 kJ/mol |
| Standard molar entropy S |
13.8 J·K−1·mol−1 |
| Hazards | |
| MSDS | External MSDS |
| EU classification | Highly toxic (T+) Carc. Cat. 2 |
| R-phrases | R49, R25, R26, R36/37/38, R43, R48/23 |
| S-phrases | S53, S45 |
| Flash point | non-flammable |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Other anions | Beryllium telluride |
| Other cations | Magnesium oxide Calcium oxide |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
|
Beryllium oxide (BeO) is a white crystalline oxide. It is obtained from beryllium or beryllium compounds by ignition in the air. The sintered beryllium oxide (beryllia), which is very stable, has ceramic characteristics. It is similar to aluminium oxide (Al2O3), is highly fire resistant (melting point: 2570°C), and has polymorphism. Beryllium oxide was previously called glucina.
Beryllium oxide formed at high temperatures (>800°C) is inert but may be easily dissolved in hot aqueous ammonium bifluoride (NH4HF2) or a hot solution of concentrated sulfuric acid (H2SO4) and ammonium sulfate ((NH4)2SO4).
[edit] Applications
This complex is used for rocket engines, catalysts, semiconductors, moderators of atomic reactors, and neutron reflectors.
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. Some power semiconductor devices have used beryllium oxide ceramic to insulate the silicon chip from the metal mounting base of the package in order to achieve a lower value thermal resistance than for a similar construction made with aluminium oxide. It is also used as a structural ceramic for high-performance vacuum tubes, magnetrons, and gas lasers.
[edit] Safety
BeO is carcinogenic if the powder is ingested or inhaled and may cause chronic beryllium disease.
