| 词条 | Hafnium(IV) carbide |
| 释义 |
| Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 437634684 | Name = Hafnium(IV) carbide | ImageFile =NaCl polyhedra.png | ImageName = Hafnium(IV) carbide | OtherNames = |Section1={{Chembox Identifiers | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 17340381 | InChI = 1/C.Hf/q-1;+1/rCHf/c1-2 | SMILES = [Hf+]#[C-] | InChIKey = NVDNLVYQHRUYJA-GLWNXBRTAK | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/C.Hf/q-1;+1 | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = NVDNLVYQHRUYJA-UHFFFAOYSA-N | CASNo_Ref = {{cascite|correct|CAS}} | CASNo = 12069-85-1 | PubChem = 16212551 |Section2={{Chembox Properties | Formula = HfC | MolarMass = 190.50 g/mol | Appearance = black odorless powder | Density = 12.2 g/cm3[1] | Solubility = insoluble | MeltingPtC = 3900 | MeltingPt_ref = [2] | BoilingPt = |Section3={{Chembox Structure | CrystalStruct = cubic, cF8 | SpaceGroup = Fm3m, No. 225 }} |Section7={{Chembox Hazards | EUClass = not listed | NFPA-H = 2 | NFPA-R = 1 | NFPA-F = 2 }}Hafnium carbide (HfC) is a chemical compound of hafnium and carbon. With a melting point of about 3900 °C it is one of the most refractory binary compounds known.[2] However, it has a low oxidation resistance, with the oxidation starting at temperatures as low as 430 °C.[2] Hafnium carbide is usually carbon deficient and therefore its composition is often expressed as HfCx (x = 0.5 to 1.0). It has a cubic (rock-salt) crystal structure at any value of x.[3] Hafnium carbide powder is obtained by the reduction of hafnium(IV) oxide with carbon at 1800 to 2000 °C. A long processing time is required to remove all oxygen. Alternatively, high-purity HfC coatings can be obtained by chemical vapor deposition from a gas mixture of methane, hydrogen, and vaporized hafnium(IV) chloride. Because of the technical complexity and high cost of the synthesis, HfC has a very limited use, despite its favorable properties such as high hardness (>9 Mohs[4]) and melting point.[5] The magnetic properties of HfCx change from paramagnetic for x ≤ 0.8 to diamagnetic at larger x. An inverse behavior (dia-paramagnetic transition with increasing x) is observed for TaCx, despite its having the same crystal structure as HfCx.[6] References1. ^Physical Constants of Inorganic Compounds in {{RubberBible86th|pages=4–44 ff.}} {{Hafnium compounds}}{{Use dmy dates|date=March 2018}}{{Inorganic-compound-stub}}2. ^{{cite journal|doi=10.1111/j.1151-2916.1992.tb05487.x | title=Oxidation Kinetics of Hafnium Carbide in the Temperature Range of 480o to 600oC | journal=Journal of the American Ceramic Society | date=1992 | volume=75 | issue=10 | pages=2671–2678 | first=Shiro | last=Shimada}} 3. ^{{cite journal|title=Electronic structure of cubic HfxTa1–xCy carbides from X-ray spectroscopy studies and cluster self-consistent calculations|doi=10.1016/j.jallcom.2007.08.018|year=2008|last1=Lavrentyev|first1=A|last2=Gabrelian|first2=B|last3=Vorzhev|first3=V|last4=Nikiforov|first4=I|last5=Khyzhun|first5=O|last6=Rehr|first6=J|journal=Journal of Alloys and Compounds|volume=462|pages=4–10|issue=1-2}} 4. ^CRC Materials Science and Engineering Handbook (2001). 5. ^1 2 {{cite book|author=Harry Julius Emeléus|title=Advances in Inorganic Chemistry and Radiochemistry|url=https://books.google.com/books?id=-SnCsg5jM_kC&pg=PA169|accessdate=3 May 2011|year=1968|publisher=Academic Press|isbn=978-0-12-023611-4|pages=169–170}} 6. ^{{cite book|author1=Aleksandr Ivanovich Gusev|author2=Andreĭ Andreevich Rempel|author3=Andreas J. Magerl|title=Disorder and order in strongly nonstoichiometric compounds: transition metal carbides, nitrides, and oxides|url=https://books.google.com/books?id=jc2D7TGZcyUC&pg=PA513|accessdate=3 May 2011|year=2001|publisher=Springer|isbn=978-3-540-41817-7|pages=513–516}} 2 : Carbides|Hafnium compounds |
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