Rhenium

Rhenium is a silvery-white metallic element with the symbol Re and atomic number 75. It has an atomic weight of 186.207 u and a very high density of 21.02 g/cm3. Rhenium has one of the highest melting points of all elements at 3180°C and a boiling point of 5596°C. It mainly occurs in a +7 oxidation state. Rhenium is one of the rarest stable elements, typically extracted from molybdenum roaster-flue dusts.

In electronics, rhenium finds specialty uses where high temperatures are involved. It is commonly alloyed with tungsten to produce tungsten-rhenium filaments for mass spectrometers, vacuum tubes, and some light bulbs. These filaments can operate at very high temperatures. Rhenium-molybdenum and rhenium-tantalum alloys are also used for furnace windings and heating elements capable of withstanding intense heat.

Rhenium is also used as a coating material, e.g. Re sputter target, in semiconductor manufacturing to enable greater wear resistance and reactor performance. Rhenium compounds like copper rhenium sulfide are applied as semi-conductors. Overall, rhenium’s extraordinary resistance to heat, wear, and corrosion makes it a unique metallic element for demanding electronic and optical applications, despite its high price.