Hafnium( Hf)

Hafnium is a chemical element  with the symbol  Hf and atomic number  72.    A lustrous , silvery gray, tetravalent  transition metal , hafnium chemically resembles zirconium  and is found in zirconium minerals .    Its existence was predicted by Dmitri Mendeleev  in 1869.    Hafnium was the penultimate stable isotope  element to be discovered (rhenium  was identified two years later).    Hafnium is named for 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 capture  cross-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.
 
■   General Properties for Hafnium
○   Symbol  :  Hf
○   Atomic Number  :  72
○   Atomic Weight  :  178.49
○   Density (near r.t)  :  13.31 g.cm-3
○   Liquid density at m.p  :  12 g.cm-3
○   Melting Point  :  2233 °C
○   Boiling Point  :  4603 °C