Molybdenum (Mo) is a silvery-grey transition metal in the 5th period of the periodic table. Its high hardness and high melting point of 2623 °C identify molybdenum as a refractory metal. The name molybdenum is based on the Ancient Greek word “molybdos” representing “lead”, due to initial confusion with lead ores. Molybdenum does not occur as a native metal, but can be found in various oxidation states within a variety of minerals. The principal ore for molybdenum extraction is molybdenite (MoS2).
Molybdenum did not play an important commercial role until being used in armor plating and as a substitute for tungsten in high-speed steels during World War I. Until today, it is utilized as an alloying element to enhance strength, hardness, corrosion- and heat resistance. This makes it attractive for a wide range of applications: aircraft engine components, glass-melting electrodes, wires for lighting, hot-zones and sputter targets (…). Molybdenum thin films produced by sputtering are integral parts of thin-film transistors in TFT-LCD displays. In a CIGS photovoltaic cell, a molybdenum thin film is used as backing plate for the absorber film.