after hafnia. latin for: copenhagen, where it was discovered
dmitri mendeleev (1869)
discovery and first isolation
dirk coster and george de hevesy (1922)
main isotopes of hafnium
hafnium is a chemical element with the symbolhf and atomic number 72. a lustrous, silvery gray, tetravalenttransition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals. its existence was predicted by dmitri mendeleev in 1869, though it was not identified until 1923, by coster and hevesy, making it the last stable element to be discovered. hafnium is named after hafnia, the latin name for copenhagen, where it was discovered.
hafnium is used in filaments and electrodes. some semiconductor fabrication processes use its oxide for integrated circuits at 45 nm and smaller feature lengths. some superalloys used for special applications contain hafnium in combination with niobium, titanium, or tungsten.
hafnium's large neutron capturecross section makes it a good material for neutron absorption in control rods in nuclear power plants, but at the same time requires that it be removed from the neutron-transparent corrosion-resistant zirconium alloys used in nuclear reactors.