Misplaced Pages

Hafnium diboride: Difference between revisions

Article snapshot taken from Wikipedia with creative commons attribution-sharealike license. Give it a read and then ask your questions in the chat. We can research this topic together.
Browse history interactively
Page 1
Page 2
← Previous editContent deleted Content addedVisualWikitext
Revision as of 22:28, 13 August 2011 editCheMoBot (talk | contribs)Bots141,565 edits Updating {{chembox}} (no changed fields - updated 'DrugBank_Ref', 'UNII_Ref', 'ChEMBL_Ref', 'ChEBI_Ref', 'KEGG_Ref', 'StdInChI_Ref', 'StdInChIKey_Ref', 'ChEBI_Ref') per Chem/Drugbox validation (r← Previous edit Latest revision as of 19:07, 27 April 2024 edit undoCitation bot (talk | contribs)Bots5,391,210 edits Alter: volume, pages. Added issue. Formatted dashes. | Use this bot. Report bugs. | Suggested by Whoop whoop pull up | Category:Borides | #UCB_Category 35/37 
(29 intermediate revisions by 19 users not shown)
Line 1: Line 1:
{{Unreferenced stub|auto=yes|date=December 2009}} {{More citations needed|date=December 2009}}
{{Chembox {{Chembox
|Verifiedfields = changed
⚫ | verifiedrevid = 396491694
|Watchedfields = changed
⚫ | ImageFile = Magnesium-diboride-3D-balls.png
⚫ |verifiedrevid = 444704876
| ImageSize =
⚫ |ImageFile = Magnesium-diboride-3D-balls.png
| IUPACName =
⚫ |Section1={{Chembox Identifiers
| OtherNames =
⚫ |ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
⚫ | Section1 = {{Chembox Identifiers
⚫ |ChemSpiderID = 21241816
⚫ | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
⚫ |InChI = 1/B2.Hf/c1-2;/q+2;-2/rB2Hf/c1-2-3-1
⚫ | ChemSpiderID = 21241816
⚫ |InChIKey = MELCCCHYSRGEEL-KRVKJWMQAC
⚫ | InChI = 1/B2.Hf/c1-2;/q+2;-2/rB2Hf/c1-2-3-1
⚫ |StdInChI_Ref = {{stdinchicite|correct|chemspider}}
⚫ | InChIKey = MELCCCHYSRGEEL-KRVKJWMQAC
⚫ |StdInChI = 1S/B2.Hf/c1-2;/q+2;-2
⚫ | StdInChI_Ref = {{stdinchicite|correct|chemspider}}
⚫ |StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
⚫ | StdInChI = 1S/B2.Hf/c1-2;/q+2;-2
⚫ |StdInChIKey = MELCCCHYSRGEEL-UHFFFAOYSA-N
⚫ | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
⚫ |CASNo = 12007-23-7
⚫ | StdInChIKey = MELCCCHYSRGEEL-UHFFFAOYSA-N
⚫ |CASNo_Ref = {{cascite|correct|CAS}}
⚫ | CASNo = 12007-23-7
⚫ |PubChem = 6336857
⚫ | CASNo_Ref = {{cascite|correct|CAS}}
⚫ |SMILES = B\1=B\/1
⚫ | PubChem =
⚫ | SMILES = B\1=B\/1
}} }}
| Section2 = {{Chembox Properties |Section2={{Chembox Properties
| Formula = HfB<sub>2</sub> |Formula = HfB<sub>2</sub>
| MolarMass = 200.11 g/mol |MolarMass = 200.11 g/mol
|Density = 11.2 g/cm<sup>3</sup> <ref>{{cite journal |last1=Fahrenholtz |first1=William |title=Refractory diborides of zirconium and hafnium |journal=Journal of the American Ceramic Society |date=10 May 2007 |volume=90 |issue=5 |pages=1347–1364 |doi=10.1111/j.1551-2916.2007.01583.x |url=https://doi.org/10.1111/j.1551-2916.2007.01583.x}}</ref>
| Appearance =
|MeltingPt = ca.
| Density = 10.5 g/cm<sup>3</sup>
| MeltingPt = ca. 3250 °C |MeltingPtC = 3250
| BoilingPt =
| Solubility =
}} }}
| Section3 = {{Chembox Structure |Section3={{Chembox Structure
| CrystalStruct = Hexagonal, ] |CrystalStruct = Hexagonal, ]
| SpaceGroup = P6/mmm, No. 191 |SpaceGroup = P6/mmm, No. 191
}}
| Section7 = {{Chembox Hazards
| MainHazards =
| FlashPt =
| Autoignition =
}} }}
}} }}


'''Hafnium diboride''' is an ultra-high temperature ] composed of ] and ]. It has a melting temperature of about 3250 degrees Celsius. It is an unusual ceramic, having relatively high ] and ]. It is a grey, metallic looking material. Hafnium diboride has a hexagonal ] structure, a ] of 200.11 grams per mole, and a density of 10.5 grams per cubic centimeter. '''Hafnium diboride''' is a type of ] composed of ] and ] that belongs to the class of ]s. It has a melting temperature of about 3250 °C. It is an unusual ceramic, having relatively high ] and ], properties it shares with ] ] and ]. It is a grey, metallic looking material. Hafnium diboride has a hexagonal ] structure, a ] of 200.11 grams per mole, and a density of 11.2 g/cm<sup>3</sup>.


Hafnium diboride is often combined with ], ], ], ], and/or ] to improve the consolidation of the hafnium diboride powder (]). It is commonly formed into a solid by a process called ], where the powders are pressed together using both heat and pressure. Hafnium diboride is often combined with ], ], ], ], and/or ] to improve the consolidation of the hafnium diboride powder (]). It is commonly formed into a solid by a process called ], where the powders are pressed together using both heat and pressure.


The material has potential for use in hypervelocity reentry vehicles such as ] ]s or aerodynamic ], due to its strength and thermal properties. Unlike polymer and composite material, HfB<sub>2</sub> can be formed into aerodynamic shapes that will not ] during reentry. The material has potential for use in hypervelocity ] vehicles such as ] ]s or aerodynamic ], due to its strength and thermal properties. Unlike polymer and composite material, HfB<sub>2</sub> can be formed into aerodynamic shapes that will not ] during reentry.


Hafnium diboride is also investigated as a possible new material for ] ]s. Hafnium diboride is also investigated as a possible new material for ] ]s.
It is also being investigated as a microchip ]. If synthesized correctly, the barrier can be less than 7&nbsp;nm thick. It is also being investigated as a microchip ]. If synthesized correctly, the barrier can be less than 7&nbsp;nm in thickness.

Nanocrystals of HfB<sub>2</sub> with rose-like morphology were obtained combining HfO<sub>2</sub> and NaBH<sub>4</sub> at 700-900°C under argon flow:<ref>{{cite journal|last1=Zoli|first1=Luca|last2=Galizia|first2=Pietro|last3=Silvestroni|first3=Laura|last4=Sciti|first4=Diletta|title=Synthesis of group IV and V metal diboride nanocrystals via borothermal reduction with sodium borohydride|journal=Journal of the American Ceramic Society|date=23 January 2018|volume=101|issue=6|pages=2627–2637|doi=10.1111/jace.15401|url=https://zenodo.org/record/1292491|doi-access=free}}</ref>

HfO<sub>2</sub> + 3NaBH<sub>4</sub> → HfB<sub>2</sub> + 2Na(g,l) + NaBO<sub>2</sub> + 6H<sub>2</sub>(g)

== References ==
{{reflist}}


{{Hafnium compounds}} {{Hafnium compounds}}
{{Borides}}


{{DEFAULTSORT:Hafnium Diboride}} {{DEFAULTSORT:Hafnium Diboride}}
Line 56: Line 56:
] ]
] ]


{{Inorganic-compound-stub}}