zirconium (Zr), chemical element, metal of Group 4 (IVb) of the periodic table, used as a structural material for nuclear reactors.

Zirconium is a gray metal that has the distinction of being the last element symbol, alphabetically, of the periodic table. This element finds use in alloys, particularly for nuclear applications.

Zr is a reactive metal and usually found as oxide, ZrO 2. The oxide is reduced to sub-oxides by argon ion bombardment. Commonly seen as minor components in Hf-containing compounds.