Beryllium oxide

Crystal structure
__ Be 2+      __ O 2−
General
Surname	Beryllium oxide
other names	Beryl clay
Ratio formula	BeO
Brief description	white, odorless solid
External identifiers / databases
CAS number 1304-56-9 EC number 215-133-1 ECHA InfoCard 100,013,758 PubChem 14775 ChemSpider 14092 Wikidata Q422714
properties
Molar mass	25.01 g mol −1
Physical state	firmly
density	3.01 g cm −3
Melting point	2575 ° C
boiling point	approx. 3900 ° C
solubility	almost insoluble in water
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary danger H and P phrases H: 301-315-317-319-330-335-350i-372 P: 201-260-280-284-301 + 310-305 + 351 + 338
MAK	not specified, as carcinogenic
Thermodynamic properties
ΔH f 0	−609.4 kJ / mol
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Beryllium oxide (BeO, also: beryl alumina ) is the metal oxide of the chemical element beryllium and a highly toxic substance that is used, among other things, as a ceramic material.

Occurrence

Beryllium oxide also occurs naturally as a mineral and is then called bromellite . It is found in Långban / Sweden.

Extraction and presentation

Beryllium oxide has been made commercially for over 50 years.

In the primary industrial synthesis process, high-quality beryllium hydroxide is dissolved in sulfuric acid. The solution is filtered to remove insoluble oxide and sulfate contaminants. The resulting clear filtrate is concentrated by evaporation and crystallizes on cooling of high-purity beryllium sulfate. This is calcined at carefully controlled temperatures between 1150 and 1450 ° C, which have been selected to give the beryllium oxide powders the tailored properties required by individual beryllia ceramic manufacturers.

It can also be made by reacting beryllium with oxygen .

${\displaystyle {\ce {2 Be + O2 -> 2 BeO}}}$

properties

It has in addition to the above characteristics a very high hardness and is at a relatively low density highly dielectric strength .

Beryllium oxide is particularly well attacked by concentrated acids . In contrast to other alkaline earth metal oxides, it forms a wurtzite structure due to the small size of the ion .

use

Since beryllium oxide ceramic with 300 W / ( mK ) conducts heat extremely well at room temperature and is also electrically well insulated, it is used in thermocouple protection tubes, melting crucibles , spark plugs , in electronics as a heat sink for semiconductor components and in reactor technology . As a single crystal grown stoichiometrically together with aluminum oxide and doped with chromium , beryllium oxide is used as a solid-state laser material in medicine under the name of alexandrite , which emits at a wavelength of 755 nm.

The ceramic properties of sintered beryllium oxide make it suitable for manufacturing or protecting materials that are used at high temperatures in corrosive environments. It is used in lasers and electronics (e.g. transistor holders, semiconductor housings, microelectronic substrates, microwave devices, high-power laser tubes), in aerospace and military applications (e.g. gyroscopes and armor), refractory materials (e.g. thermocouple sleeves and crucibles), nuclear technology (reactor fuels and moderators) and medical / dental applications (e.g. ceramic crowns). It is also used as an additive (to glass, ceramics and plastics) in the production of beryllium compounds and as a catalyst for organic reactions.

Its use is limited due to its toxicity. The processing of the material has been strictly controlled for 30 years because of its toxicity, components containing beryllium oxide must be labeled. In many areas it is replaced by the non-toxic boron nitride or aluminum nitride , which also conducts heat well and has an electrically insulating effect.

Individual evidence

1. ↑ ^{a b c d e f} Entry on beryllium oxide in the GESTIS substance database of the IFA , accessed on January 8, 2018(JavaScript required) .
2. ↑ ^{a b} Data sheet Beryllium oxide at AlfaAesar, accessed on February 4, 2018 ( PDF )(JavaScript required) .
3. ↑ Entry on beryllium oxide in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
4. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-6.
5. ↑ Gmelins Handbuch der Inorganischen Chemie, BERYLLIUM, system number 26, eighth edition, Verlag Chemie GmbH Berlin 1930.
6. ↑ Kenneth A. Walsh: Beryllium Chemistry and Processing . ASM International, 2009, ISBN 978-0-87170-721-5 , pp. 122 ( limited preview in Google Book search).
7. ↑ Periodic Table: Beryllium: Periodic Table: Beryllium , accessdate: July 25, 2019
8. ↑ materion.com: CC-001 BeO Ceramics Thermal Management Solutions ( Memento of the original dated July 3, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 94 kB), accessed on June 14, 2013. 
9. ↑ Peter Horvath, Dirk Meyer-Rogge, Ellen Maushagen: Hypertrichosis - Photoepilation with the alexandrite laser. (PDF; 154 kB)  ( Page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.  
10. ↑ NCBI Bookshelf: BERYLLIUM AND BERYLLIUM COMPOUNDS - Arsenic, Metals, Fibers and Dusts - NCBI Bookshelf , access date : July 25, 2019