Hafnium Compounds
Hafnium compounds are compounds containing the element hafnium (Hf). Due to the lanthanide contraction, the ionic radius of hafnium(IV) (0.78 ångström) is almost the same as that of zirconium(IV) (0.79 angstroms). Consequently, compounds of hafnium(IV) and zirconium(IV) have very similar chemical and physical properties. Hafnium and zirconium tend to occur together in nature and the similarity of their ionic radii makes their chemical separation rather difficult. Hafnium tends to form inorganic compounds in the oxidation state of +4. Halogens react with it to form hafnium tetrahalides. At higher temperatures, hafnium reacts with oxygen, nitrogen, carbon, boron, sulfur, and silicon. Some compounds of hafnium in lower oxidation states are known.
Compounds of hafnium have been studied mostly to develop methods of separating hafnium from zirconium, producing the metal, and comparing properties with similar zirconium compounds. Although the properties of inorganic hafnium and zirconium compounds are generally comparable, differences in chemical behavior become more evident in organometallic compounds.
Hafnium compounds are recognized as some of the most heat-resistant materials available today. Leveraging the remarkable properties of hafnium, these compounds are designed to endure and perform in environments requiring extreme thermal stability and resilience. Their unique characteristics make them indispensable across various high-stakes industries, including aerospace, nuclear energy, and advanced manufacturing.
Hafnium Compounds Product List
Hafnium Chloride
Hafnium Oxide
Hafnium Carbide
Hafnium Fluoride
Hafnium Nitride
Hafnium Diselenide
Hafnium Disulfide
Hafnium Iodide
Hafnium Carbonitride
Hafnium Diboride
Hafnium Boride
Hafnium Hydride
Hafnium(Iv) Sulfate
Hafnium Titanate
Hafnium Telluride
Hafnium Disilicide
Hafnium Lead Oxide Powder
Hafnium Ditelluride Crystals
Hafnium(Iv) Oxychloride Hydrate
Bis(Cyclopentadienyl)Hafnium(Iv) Dichloride
Bis(Pentamethylcyclopentadienyl)Hafnium Dichloride
Bis(Tert-Butylcyclopentadienyl)Hafnium(Iv) Dichloride
Zirconium Hafnium Niobium Carbide Solid Solution Powder
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Hafnium diboride belongs to the class of ultra-high temperature ceramics, a type of refractory ceramic composed of hafnium and boron. It has a melting temperature of about 3250 °C. This ceramic composite is noted for its high thermal conductivity and excellent oxidation resistance. Hafnium diboride is commonly used in ultra-high-temperature applications, such as the thermal protection systems of hypersonic vehicles. It is an unusual ceramic, having relatively high thermal and electrical conductivities, properties it shares with isostructural titanium diboride and zirconium diboride. Nanocrystals of HfB2 with rose-like morphology were obtained combining HfO2 and NaBH4 at 700-900°C under argon flow:
HfO2 + 3NaBH4 → HfB2 + 2Na(g,l) + NaBO2 + 6H2(g)
Hafnium carbide is the most refractory binary compound known, with a melting point over 3,890 °C, and hafnium nitride is the most refractory of all known metal nitrides, with a melting point of 3,310 °C. This has led to proposals that hafnium or its carbides might be useful as construction materials that are subjected to very high temperatures. Hafnium carbide is often used in high-temperature ceramics and coatings. Its ability to withstand extreme temperatures makes it ideal for use in the aerospace and industrial sectors.
The mixed carbide tantalum hafnium carbide (Ta4HfC5) possesses the highest melting point of any currently known compound, 4,263 K (3,990 °C; 7,214 °F). Recent supercomputer simulations suggest a hafnium alloy with a melting point of 4,400 K. Among hafnium composites, tantalum hafnium carbide is particularly noteworthy. This material, a combination of tantalum, hafnium, and carbon, has an extraordinary melting point of approximately 3,988°C, making it one of the most heat-resistant materials known. Its applications include components for hypersonic vehicles, rocket nozzles, and parts in nuclear reactors.
Hafnium forms both a hafnium(III) and a hafnium(IV) nitride.
Hafnium Nitride (HfN), with good electrical conductivity and thermal stability, hafnium nitride is used in electronics and as a high-temperature structural material. It is particularly useful in environments where both electrical and thermal performance are critical.
Hafnium silicate (HfSiO4) is a silicate of hafnium, and it is a tetragonal crystal. Thin films of hafnium silicate and zirconium silicate grown by atomic layer deposition, chemical vapor deposition or MOCVD, can be used as a high-k dielectric as a replacement for silicon dioxide in modern semiconductor devices. Hafnium(IV) nitrate (Hf(NO3)4) is the nitrate of hafnium(IV). It can be prepared by the reaction of hafnium tetrachloride and dinitrogen pentoxide.
Hafnium disulfide is a layered dichalcogenide with the chemical formula of HfS2. A few atomic layers of this material can be exfoliated using the standard Scotch Tape technique (see graphene) and used for the fabrication of a field-effect transistor. High-yield synthesis of HfS2 has also been demonstrated using liquid phase exfoliation, resulting in the production of stable few-layer HfS2 flakes. Hafnium disulfide powder can be produced by reacting hydrogen sulfide and hafnium oxides at 500–1300 °C.