Niobium (metallic element)

Niobium, chemical symbol Nb, is a lustrous gray metal with paramagnetism, atomic number 41, atomic weight 92.90638, belonging to the Ⅴ B group on the periodic table of elements. In 1801, C. hachet isolated an oxide of a new element from niobium and named it columbium. The melting point is 2468 ℃, the boiling point is 4742 ℃, and the density is 8.57g/cm 3. High purity niobium has high ductility, but it will harden with the increase of impurity content. The capture cross section of niobium for thermal neutron is very low, so it is very useful in nuclear industry.