Niobium is a kind of metal element. Chemical symbol Nb, atomic number 41, atomic weight 92.90638, belongs to the family VB of periodic system. In 1801, British C. hatchet separated a new element oxide from niobium ore and named it columbium. Niobium is a gray white metal with a melting point of 2468 ℃, a boiling point of 4742 ℃, and a density of 8.57g/cm3. Niobium is a gray metal with luster, which has paramagnetism and belongs to 5 groups of periodic table. The ductility of high purity niobium metal is higher, but it will harden with the increase of impurity content. Niobium has a very low capture cross section for thermal neutrons, so it is quite useful in the nuclear industry.