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Natural hafnium (72 Hf) consists of five observationally stable isotopes (176 Hf, 177 Hf, 178 Hf, 179 Hf, and 180 Hf) and one very long-lived radioisotope, 174 Hf, with a half-life of 3.8 × 10 16 years. [2] In addition, there are 34 known synthetic radioisotopes, the most stable of which is 182 Hf with a half-life of 8.9 × 10 6 years.
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. It is an unusual ceramic, having relatively high thermal and electrical conductivities, properties it shares with isostructural titanium diboride and zirconium ...
HF is also widely used in the petrochemical industry as a component of superacids. Due to strong and extensive hydrogen bonding, it boils near room temperature, a much higher temperature than other hydrogen halides. Hydrogen fluoride is an extremely dangerous gas, forming corrosive and penetrating hydrofluoric acid upon contact with moisture.
The radioactive isotopes' half-lives range from 400 ms for 153 Hf [16] to 7.0 × 10 16 years for the most stable one, the primordial 174 Hf. [ 15 ] [ 18 ] The extinct radionuclide 182 Hf has a half-life of 8.9 ± 0.1 million years , and is an important tracker isotope for the formation of planetary cores . [ 19 ]
National Physical Laboratory, Kaye and Laby Tables of Physical and Chemical Constants; D. Ambrose, M.B. Ewing, M.L. McGlashan, Critical constants and second virial coefficients of gases (retrieved Dec 2005)
Group 4 is the second group of transition metals in the periodic table. It contains only the four elements titanium (Ti), zirconium (Zr), hafnium (Hf), and rutherfordium (Rf). ). The group is also called the titanium group or titanium family after its lightest me
Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water.Solutions of HF are colorless, acidic and highly corrosive.A common concentration is 49% (48-52%) but there are also stronger solutions (e.g. 70%) and pure HF has a boiling point near room temperature.
Hafnium carbide (Hf C) is a chemical compound of hafnium and carbon.Previously the material was estimated to have a melting point of about 3,900 °C. [2] More recent tests have been able to conclusively prove that the substance has an even higher melting point of 3,958 °C exceeding those of tantalum carbide and tantalum hafnium carbide which were both previously estimated to be higher. [3]