Terbium

Terbium, chemical element, symbol Tb; for physical constants see Periodic Table. Terbium was discovered by C.G. Mosander in 1843. It is found in cerite, and gadolinite and is obtained commercially from monazite. The metal is prepared by reducing the anhydrous fluoride with calcium. Terbium is silvery-white, soft, malleable, ductile metal. Ion-exchange and solvent extraction techniques have led to much easier isolation of the so-called rare-earth elements. Terbium and its compounds are finding use in laser materials, solid-state devices, color TV phosphors, and fuel cells.