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{{Chembox {{Chembox
| Verifiedfields = changed
| verifiedrevid = 404695937
| Watchedfields = changed
| ImageFile = Wurtzite polyhedra.png
| verifiedrevid = 442353803
| ImageFile_Ref = {{chemboximage|correct|??}}
| ImageFile = Wurtzite polyhedra.png
| ImageSize = 244
| ImageFile_Ref = {{chemboximage|correct|??}}
| ImageName = Unit cell ball and stick model of beryllium oxide
| ImageName = Unit cell, ball and stick model of beryllium oxide
| IUPACName = Beryllium oxide
| ImageFile2 = BeO sample.jpg
| SystematicName =
| PIN = Beryllium(II) monoxide
| OtherNames = Berlox<br />
| SystematicName = Oxoberyllium
Beryllia<br />
| OtherNames = Beryllia, Thermalox, Bromellite, Thermalox 995.<ref>{{Cite web|title = beryllium oxide – Compound Summary|url = https://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=14775&loc=ec_rcs|work = PubChem Compound|publisher = National Center for Biotechnology Information|access-date = 8 November 2011|location = USA|date = 27 March 2005|at = Identification and Related records}}</ref>
Beryllia ceramic<br />
| Section1 = {{Chembox Identifiers
]<br />
| CASNo = 1304-56-9
Super beryllia<br />
| CASNo_Ref = {{cascite|correct|CAS}}
Thermalox
| UNII_Ref = {{fdacite|correct|FDA}}
| Section1 = {{Chembox Identifiers
| CASNo = 1304-56-9 | UNII = 2S8NLR37S3
| PubChem = 14775
| CASNo_Ref = {{cascite|correct|CAS}}
| PubChem = 14775 | ChemSpiderID = 14092
| PubChem_Ref = {{Pubchemcite|correct|PubChem}} | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| EINECS = 215-133-1
| ChemSpiderID = 14092
| UNNumber = 1566
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| MeSHName = beryllium+oxide
| EINECS = 215-133-1
| UNNumber = 1566 | ChEBI = 62842
| ChEBI_Ref = {{ebicite|changed|EBI}}
| MeSHName = Beryllium+oxide
| RTECS = DS4025000 | RTECS = DS4025000
| SMILES = | Beilstein = 3902801
| SMILES1 = =O | SMILES = =
| StdInChI = 1S/Be.O | SMILES1 = #
| StdInChI = 1S/Be.O
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| InChI = 1/Be.O/rBeO/c1-2
| StdInChIKey = LTPBRCUWZOMYOC-UHFFFAOYSA-N | InChI = 1/Be.O/rBeO/c1-2
| StdInChIKey = LTPBRCUWZOMYOC-UHFFFAOYSA-N
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| InChIKey = LTPBRCUWZOMYOC-SRAGPBHZAE}} | InChIKey = LTPBRCUWZOMYOC-SRAGPBHZAE
}}
| Section2 = {{Chembox Properties | Section2 = {{Chembox Properties
| Be = 1 | Be=1 | O=1
| Appearance = Colourless, vitreous crystals
| O = 1
| Odor = Odourless
| ExactMass = 25.007096757 g mol<sup>-1</sup>
| Density = 3.01 g/cm<sup>3</sup><ref name=crc>], p. 4.51</ref>
| Appearance = White crystals
| Odor = Odourless | MeltingPtC = 2578
| MeltingPt_ref=<ref name=crc/>
| Density = 3.02 g cm<sup>-3</sup><ref>{{RubberBible87th}}</ref>
| MeltingPtC = 2507 | BoilingPtC =
| BoilingPtC = 3900 | Solubility =
| SolubleOther =
| ThermalConductivity = 330 W/(m·K)
| MagSus = −11.9·10<sup>−6</sup> cm<sup>3</sup>/mol<ref>], p. 4.126</ref>
| BandGap = 10.6 eV
| BandGap = 10.6 eV<ref>{{cite journal|doi=10.1063/1.2168040 |title=Wide-band gap oxide alloy: BeZnO |date=2006 |last1=Ryu |first1=Y. R. |last2=Lee |first2=T. S. |last3=Lubguban |first3=J. A. |last4=Corman |first4=A. B. |last5=White |first5=H. W. |last6=Leem |first6=J. H. |last7=Han |first7=M. S. |last8=Park |first8=Y. S. |last9=Youn |first9=C. J. |last10=Kim |first10=W. J. |journal=Applied Physics Letters |volume=88 |issue=5 |page=052103 |bibcode=2006ApPhL..88e2103R }}</ref>
| RefractIndex = 1.7}}
| RefractIndex = n<sub>1</sub>1.7184, n<sub>2</sub>=1.733<ref>], p. 10.248</ref><ref>. webmineral</ref>
| Section3 = {{Chembox Structure
| ThermalConductivity = 210 W/(m·K)<ref>], p. 12.222</ref>
| CrystalStruct = hexagonal, ]
}}
| SpaceGroup = P6<sub>3</sub>/mc, No. 186
| Section3 = {{Chembox Structure
}}
| Structure_ref=<ref>], p. 4.139</ref>
| Section4 = {{Chembox Thermochemistry
| CrystalStruct = Hexagonal, ]
| Reference = <ref>{{CODATA thermo}}.</ref>
| SpaceGroup = P6<sub>3</sub>mc
| DeltaHf = –609.4(25) kJ mol<sup>−1</sup>
| PointGroup = C<sub>6v</sub>
| Entropy = 13.77(4) J K<sup>–1</sup> mol<sup>–1</sup>
| MolShape = Linear
}}
| UnitCellFormulas = 2
| Section7 = {{Chembox Hazards
| LattConst_a = 2.6979 Å
| EUClass = ]<br/>Highly toxic ('''T+''')<br />Irritant ('''Xi''')
| LattConst_c = 4.3772 Å
| EUIndex = 004-003-00-8
}}
| GHSPictograms = {{GHS06|Acte Tox. 2, Acute Tox. 3}}{{GHS08|Carc. 1B, STOT RE 1, STOT SE 3, Skin Sens. 1, Eye Irrit. 2, Skin Irrit. 2}}
| Section4 = {{Chembox Thermochemistry
| GHSSignalWord = DANGER
| Thermochemistry_ref =<ref>], pp. 5.1, 5.6, 6.155</ref>
| HPhrases = {{H-phrases|350|330|301|372|319|335|315|317}}
| DeltaHf = −609.4±2.5 kJ/mol
| DeltaGf = −580.1 kJ/mol
| Entropy = 13.77±0.04 J/(K·mol)
| HeatCapacity = 25.6 J/(K·mol)
| DeltaHfus = 86 kJ/mol
}}
| Section5 = {{Chembox Hazards
| MainHazards = Very toxic, Group 1B carcinogen
| GHSPictograms = {{GHS skull and crossbones}} {{GHS health hazard}}{{GHS environment}}
| GHSSignalWord = '''DANGER'''
| HPhrases = {{H-phrases|301|315|317|319|330|335|350|372}}
| PPhrases = {{P-phrases|201|260|280|284|301+310|305+351+338}}
| NFPA-H = 4 | NFPA-H = 4
| NFPA-F = 0 | NFPA-F = 0
| NFPA-R = 0 | NFPA-R = 0
| LD50 = 15 mg/kg (mouse, oral)<ref>Beryllium oxide toxicity</ref>
| RPhrases = {{R49}}, {{R25}}, {{R26}}, {{R36/37/38}}, {{R43}}, {{R48/23}}

| SPhrases = {{S53}}, {{S45}}
| REL = Ca C 0.0005 mg/m<sup>3</sup> (as Be)<ref name=PGCH>{{PGCH|0054}}</ref>
| FlashPt = Non-flammable
| PEL = TWA 0.002 mg/m<sup>3</sup><br/>C 0.005 mg/m<sup>3</sup> (30 minutes), with a maximum peak of 0.025 mg/m<sup>3</sup> (as Be)<ref name=PGCH/>
| LD50 = 2062 mg/kg (mouse, oral)
| IDLH = Ca <ref name=PGCH/>
}} }}
| Section8 = {{Chembox Related | Section6 = {{Chembox Related
| OtherCations = {{unbulleted list
| OtherAnions = ]<br />]<br />]
| OtherCations = ]<br />] | ]
| ]
| ]
| ]
}} }}
| OtherAnions = ]
}} }}
}}
'''] oxide''' ('''BeO'''), also known as '''beryllia''', is an ] with the ] BeO. This white crystalline solid is notable as it is an electrical insulator with a thermal conductivity higher than any other non-metal except diamond, and actually exceeds that of some metals.<ref name = "Greenwood">{{Greenwood&Earnshaw}}</ref> Its high melting point leads to its use as a ].<ref>{{cite book|url=http://books.google.com/?id=6TKSG6LWIEQC&pg=PA301|page=301|author=Raymond Aurelius Higgins|year=2006|title=Materials for Engineers and Technicians|publisher=Newnes|isbn=0750668504}}</ref> It occurs in nature as the mineral ]. Historically beryllium oxide was called '''glucina''' or glucinium oxide.

'''Beryllium oxide''' ('''BeO'''), also known as '''beryllia''', is an ] with the ] BeO. This colourless solid is an ] with a higher ] than any other non-metal except ], and exceeds that of most metals.<ref name = "Greenwood">{{Greenwood&Earnshaw}}</ref> As an ], beryllium oxide is white. Its high melting point leads to its use as a ] material.<ref>{{cite book |url=https://archive.org/details/materialsforengi0004higg |url-access=registration |page= |author=Higgins, Raymond Aurelius |year=2006 |title=Materials for Engineers and Technicians |publisher=Newnes |isbn=0-7506-6850-4}}</ref> It occurs in nature as the mineral ]. Historically and in ], beryllium oxide was called '''glucina''' or '''glucinium oxide''', owing to its sweet taste.


==Preparation and chemical properties== ==Preparation and chemical properties==
Beryllium oxide can be prepared by calcining (roasting) beryllium carbonate, dehydrating ] or igniting the metal: Beryllium oxide can be prepared by ] (roasting) ], dehydrating ], or igniting metallic ]:
:BeCO<sub>3</sub>→ BeO + CO<sub>2</sub> :BeCO<sub>3</sub> → BeO + CO<sub>2</sub>
:Be(OH)<sub>2</sub> → BeO + H<sub>2</sub>O :Be(OH)<sub>2</sub> → BeO + H<sub>2</sub>O
:2 Be + O<sub>2</sub> → 2 BeO :2 Be + O<sub>2</sub> → 2 BeO
Igniting beryllium in air gives a mixture of BeO and the nitride Be<sub>3</sub>N<sub>2</sub>.<ref name = "Greenwood"/> Igniting beryllium in air gives a mixture of BeO and the nitride ].<ref name = "Greenwood"/> Unlike the oxides formed by the other Group 2 elements (]), beryllium oxide is ] rather than basic.
Unlike oxides formed by the other group 2 (alkaline earth metals), beryllium oxide is ] rather than basic.


Beryllium oxide formed at high temperatures (>800°C) is inert, but dissolves easily in hot aqueous ] (NH<sub>4</sub>HF<sub>2</sub/>) or a hot solution of concentrated ] (H<sub>2</sub>SO<sub>4</sub>) and ] ((NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub>). Beryllium oxide formed at high temperatures (>800&nbsp;°C) is inert, but dissolves easily in hot aqueous ] (NH<sub>4</sub>HF<sub>2</sub>) or a solution of hot concentrated ] (H<sub>2</sub>SO<sub>4</sub>) and ] ((NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub>).


==Structure== ==Structure==
BeO adopts the hexagonal ] structure form.<ref name = "Greenwood"/> In contrast, other group 2 oxides, ], ], ], ], crystallize in the cubic rock salt motif.<ref name = "Greenwood"/> At high temperature the structure transforms to a tetragonal form.<ref>{{cite book|author=A.F. Wells|year=1984|title=Structural Inorganic Chemistry|edition=5|publisher=Oxford Science Publications|isbn=0-19-855370-6}}</ref> In the vapor phase, beryllium oxide is present as discrete diatomic covalent molecules. The electronic structure of the beryllium oxide monomer is unusual, the orbital overlap only allows for one strong covalent bond to form, the other two orbitals do not overlap strongly enough to form a covalent bond, neither does it form an ionic bond. The result is a triplet diradical species, this is commonly simplified to a double bond. BeO crystallizes in the hexagonal ] structure, featuring tetrahedral Be<sup>2+</sup> and O<sup>2−</sup> centres, like ] and w-] (with both of which it is ]). In contrast, the oxides of the larger group-2 metals, i.e., ], ], ], ], crystallize in the cubic ] with octahedral geometry about the dications and dianions.<ref name = "Greenwood"/> At high temperature the structure transforms to a tetragonal form.<ref>{{cite book |author=Wells, A. F. |year=1984 |title=Structural Inorganic Chemistry |edition=5 |publisher=Oxford Science Publications |isbn=0-19-855370-6}}</ref>

In the vapour phase, beryllium oxide is present as discrete ]s. In the language of ], these molecules can be described as adopting ''sp'' ] on both atoms, featuring one ] (between one ''sp'' orbital on each atom) and one ] (between aligned ''p'' orbitals on each atom oriented perpendicular to the molecular axis). ] provides a slightly different picture with no ''net'' σ bonding (because the 2''s'' 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)<sup>2</sup>(2sσ*)<sup>2</sup>(2pπ)<sup>4</sup> (as in the isoelectronic ] molecule), where both bonds can be considered as ] from oxygen towards beryllium.<ref>{{cite book |title=Fundamentals of Spectroscopy |url=https://books.google.com/books?id=gfM9B3JshegC&pg=PA234 |access-date=29 November 2011 |publisher=Allied Publishers |isbn=978-81-7023-911-6 |pages=234}}</ref>


==Applications== ==Applications==
High-quality crystals may be grown ], or otherwise by the ]. For the most part, beryllium oxide is produced as a white amorphous powder, ] into larger shapes. Impurities, like carbon, can give rise to a variety of colours to the otherwise colourless host crystals.
] beryllium oxide, which is very stable, has ] characteristics.<ref>Günter Petzow, Fritz Aldinger, Sigurd Jönsson, Peter Welge, Vera van Kampen, Thomas Mensing, Thomas Brüning"Beryllium and Beryllium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry 2005, Wiley-VCH, Weinheim. {{DOI|10.1002/14356007.a04_011.pub2}}</ref> Beryllium oxide is used in rocket engines.


] beryllium oxide is a very stable ].<ref>Petzow, Günter; Aldinger, Fritz; Jönsson, Sigurd; Welge, Peter; van Kampen, Vera; Mensing, Thomas; Brüning, Thomas (2005) "Beryllium and Beryllium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a04_011.pub2}}</ref> Beryllium oxide is used in rocket engines{{cn|date=September 2023}} and as a transparent ] on ] ]. Metal-coated beryllium oxide (BeO) plates are used in the control systems of aircraft drive devices.<ref>{{cite web |url=https://www.samaterials.com/content/what-are-the-ceramic-materials-with-high-thermal-conductivity.html |title=What Are the Ceramic Materials With High Thermal Conductivity? |last=Trento |first=Chin |date=Dec 27, 2023 |website=Stanford Advanced Materials |access-date=Sep 3, 2024}}</ref>
Beryllium oxide is used in many high-performance semiconductor parts for applications such as radio equipment because it has good ] while also being a good electrical insulator. It is used as a filler in some thermal interface materials such as ].<ref name="apmag">{{cite journal | author=Greg Becker, Chris Lee, and Zuchen Lin | title=Thermal conductivity in advanced chips — Emerging generation of thermal greases offers advantages | journal=Advanced Packaging| year=2005 | pages=2–4 | url=http://www.apmag.com/ | accessdate=2008-03-04}}</ref> Some ]s have used beryllium oxide ceramic between the ] chip and the metal mounting base of the package in order to achieve a lower value of ] than for a similar construction made with ]. It is also used as a structural ] for high-performance microwave devices, ]s, ]s, and ]s.

Beryllium oxide is used in many high-performance ] 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 ].<ref name="apmag">{{cite journal |author1=Greg Becker |author2=Chris Lee |author3=Zuchen Lin |title=Thermal conductivity in advanced chips — Emerging generation of thermal greases offers advantages |journal=Advanced Packaging |year=2005 |pages=2–4 |url=http://www.apmag.com/ |access-date=2008-03-04 |url-status=dead |archive-url=https://web.archive.org/web/20000621233638/http://www.apmag.com/ |archive-date=June 21, 2000 }}</ref> It is also employed in ] and spreaders that cool electronic devices, such as ], lasers, and power amplifiers.<ref>{{cite web |url=https://www.preciseceramic.com/products/beryllium-oxide-ceramic.html |title=Beryllia (BeO) |website=Advanced Ceramic Materials |access-date=Oct 18, 2024}}</ref> Some ]s have used beryllium oxide ceramic between the ] chip and the metal mounting base of the package to achieve a lower value of ] than a similar construction of ]. It is also used as a structural ] for high-performance microwave devices, ]s, ]s {{citation needed|date=September 2024}}, and ]s. BeO has been proposed as a ] for naval marine high-temperature ]s (MGCR), as well as ]'s ] ] for space applications.<ref name="KiloPower Reactor Materials Study">{{cite web| last1=McClure |first1=Patrick |last2=Poston |first2=David |last3=Gibson |first3=Marc |last4=Bowman |first4=Cheryl |last5=Creasy |first5=John |title=KiloPower Space Reactor Concept – Reactor Materials Study |date=14 May 2014 |url=http://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-UR-14-23402 |access-date=21 November 2017}}</ref>


==Safety== ==Safety==
Like all beryllium compounds, BeO is ]ic and may cause chronic ]. Once fired into solid form, it is safe to handle as long as it is not subjected to any machining that generates dust.<ref></ref> Beryllium oxide ceramic is not a hazardous waste under Federal law in the USA. BeO is ]ic in powdered form<ref>{{cite web|url=https://nj.gov/health/eoh/rtkweb/documents/fs/0226.pdf|title=Hazardous Substance Fact Sheet|publisher=New Jersey Department of Health and Senior Services|access-date=August 17, 2018}}</ref> and may cause a chronic allergic-type lung disease ]. 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.<ref>{{cite web |url=https://www.americanberyllia.com/safety |title=Beryllium Oxide Safety |website=American Beryllia |access-date=2018-03-29}}</ref>


==References== ==References==
{{reflist|2}} {{Reflist|30em}}

==Cited sources==
*{{cite book |ref=Haynes| editor= Haynes, William M. | date = 2016| title = ] | edition = 97th | publisher = ] | isbn = 9781498754293}}


==External links== ==External links==
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{{Beryllium compounds}} {{Beryllium compounds}}
{{Oxides}}
{{oxygen compounds}}
{{Authority control}}


{{DEFAULTSORT:Beryllium Oxide}} {{DEFAULTSORT:Beryllium Oxide}}
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Latest revision as of 11:51, 17 November 2024

Beryllium oxide
Unit cell, ball and stick model of beryllium oxide
Names
Preferred IUPAC name Beryllium(II) monoxide
Systematic IUPAC name Oxoberyllium
Other names Beryllia, Thermalox, Bromellite, Thermalox 995.
Identifiers
CAS Number
3D model (JSmol)
Beilstein Reference 3902801
ChEBI
ChemSpider
ECHA InfoCard 100.013.758 Edit this at Wikidata
EC Number
  • 215-133-1
MeSH beryllium+oxide
PubChem CID
RTECS number
  • DS4025000
UNII
UN number 1566
CompTox Dashboard (EPA)
InChI
  • InChI=1S/Be.OKey: LTPBRCUWZOMYOC-UHFFFAOYSA-N
  • InChI=1/Be.O/rBeO/c1-2Key: LTPBRCUWZOMYOC-SRAGPBHZAE
SMILES
  • =
  • #
Properties
Chemical formula BeO
Molar mass 25.011 g·mol
Appearance Colourless, vitreous crystals
Odor Odourless
Density 3.01 g/cm
Melting point 2,578 °C (4,672 °F; 2,851 K)
Band gap 10.6 eV
Magnetic susceptibility (χ) −11.9·10 cm/mol
Thermal conductivity 210 W/(m·K)
Refractive index (nD) n11.7184, n2=1.733
Structure
Crystal structure Hexagonal, zincite
Space group P63mc
Point group C6v
Lattice constant a = 2.6979 Å, c = 4.3772 Å
Formula units (Z) 2
Molecular shape Linear
Thermochemistry
Heat capacity (C) 25.6 J/(K·mol)
Std molar
entropy (S298) 		13.77±0.04 J/(K·mol)
Std enthalpy of
formation (ΔfH298) 		−609.4±2.5 kJ/mol
Gibbs free energy (ΔfG) −580.1 kJ/mol
Enthalpy of fusion (ΔfHfus) 86 kJ/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards Very toxic, Group 1B carcinogen
GHS labelling:
Pictograms GHS06: Toxic GHS08: Health hazardGHS09: Environmental hazard
Signal word Danger
Hazard statements H301, H315, H317, H319, H330, H335, H350, H372
Precautionary statements P201, P260, P280, P284, P301+P310, P305+P351+P338
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 4: Very short exposure could cause death or major residual injury. E.g. VX gasFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
4 0 0
Lethal dose or concentration (LD, LC):
LD50 (median dose) 15 mg/kg (mouse, oral)
NIOSH (US health exposure limits):
PEL (Permissible) TWA 0.002 mg/m
C 0.005 mg/m (30 minutes), with a maximum peak of 0.025 mg/m (as Be)
REL (Recommended) Ca C 0.0005 mg/m (as Be)
IDLH (Immediate danger) Ca
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 , 100 kPa). ☒N verify (what is  ?) Infobox references
Chemical compound

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. As an amorphous solid, beryllium oxide is white. Its high melting point leads to its use as a refractory material. 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.

Preparation and chemical properties

Beryllium oxide can be prepared by calcining (roasting) beryllium carbonate, dehydrating beryllium hydroxide, or igniting metallic beryllium:

BeCO3 → BeO + CO2
Be(OH)2 → BeO + H2O
2 Be + O2 → 2 BeO

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).

Structure

BeO crystallizes in the hexagonal wurtzite structure, featuring tetrahedral Be and O 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. At high temperature the structure transforms to a tetragonal form.

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)(2sσ*)(2pπ) (as in the isoelectronic C2 molecule), where both bonds can be considered as dative bonds from oxygen towards beryllium.

Applications

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. Beryllium oxide is used in rocket engines 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.

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. It is also employed in heat sinks and spreaders that cool electronic devices, such as CPUs, lasers, and power amplifiers. 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 , 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.

Safety

BeO is carcinogenic in powdered form 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.

References

  1. "beryllium oxide – Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 27 March 2005. Identification and Related records. Retrieved 8 November 2011.
  2. ^ Haynes, p. 4.51
  3. Ryu, Y. R.; Lee, T. S.; Lubguban, J. A.; Corman, A. B.; White, H. W.; Leem, J. H.; Han, M. S.; Park, Y. S.; Youn, C. J.; Kim, W. J. (2006). "Wide-band gap oxide alloy: BeZnO". Applied Physics Letters. 88 (5): 052103. Bibcode:2006ApPhL..88e2103R. doi:10.1063/1.2168040.
  4. Haynes, p. 4.126
  5. Haynes, p. 12.222
  6. Haynes, p. 10.248
  7. Bromellite Mineral Data. webmineral
  8. Haynes, p. 4.139
  9. Haynes, pp. 5.1, 5.6, 6.155
  10. ^ NIOSH Pocket Guide to Chemical Hazards. "#0054". National Institute for Occupational Safety and Health (NIOSH).
  11. Beryllium oxide toxicity
  12. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
  13. Higgins, Raymond Aurelius (2006). Materials for Engineers and Technicians. Newnes. p. 301. ISBN 0-7506-6850-4.
  14. Wells, A. F. (1984). Structural Inorganic Chemistry (5 ed.). Oxford Science Publications. ISBN 0-19-855370-6.
  15. Fundamentals of Spectroscopy. Allied Publishers. p. 234. ISBN 978-81-7023-911-6. Retrieved 29 November 2011.
  16. Petzow, Günter; Aldinger, Fritz; Jönsson, Sigurd; Welge, Peter; van Kampen, Vera; Mensing, Thomas; Brüning, Thomas (2005) "Beryllium and Beryllium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim. doi:10.1002/14356007.a04_011.pub2
  17. Trento, Chin (Dec 27, 2023). "What Are the Ceramic Materials With High Thermal Conductivity?". Stanford Advanced Materials. Retrieved Sep 3, 2024.
  18. Greg Becker; Chris Lee; Zuchen Lin (2005). "Thermal conductivity in advanced chips — Emerging generation of thermal greases offers advantages". Advanced Packaging: 2–4. Archived from the original on June 21, 2000. Retrieved 2008-03-04.
  19. "Beryllia (BeO)". Advanced Ceramic Materials. Retrieved Oct 18, 2024.
  20. McClure, Patrick; Poston, David; Gibson, Marc; Bowman, Cheryl; Creasy, John (14 May 2014). "KiloPower Space Reactor Concept – Reactor Materials Study". Retrieved 21 November 2017.
  21. "Hazardous Substance Fact Sheet" (PDF). New Jersey Department of Health and Senior Services. Retrieved August 17, 2018.
  22. "Beryllium Oxide Safety". American Beryllia. Retrieved 2018-03-29.

Cited sources

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Beryllium compounds
Beryllium(I)
Beryllium(II)
Oxides
Mixed oxidation states
+1 oxidation state
+2 oxidation state
+3 oxidation state
+4 oxidation state
+5 oxidation state
+6 oxidation state
+7 oxidation state
+8 oxidation state
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