Iridium (Ir) is a dense, silvery-white transition metal grouped with other precious metals in the Platinum Group Metals (PGMs). Its atomic structure features a lattice of atoms surrounded by a sea of delocalized electrons, which allows charge carriers to move freely when a voltage is applied. This fundamental structure means that iridium conducts electricity. Iridium exhibits excellent electrical conductivity, making it suitable for specialized applications where its unique combination of properties is required.
Iridium’s Electrical Conductivity
The mechanism that allows iridium to conduct electricity is metallic bonding, where outer-shell electrons are shared across the entire metallic structure. This free movement of electrons defines electrical conductivity and is a common trait among the Platinum Group Metals, including platinum, palladium, and rhodium.
While iridium is an efficient conductor, it does not match the performance of common conductors like copper or silver. Copper, for example, is approximately 50 times more conductive than platinum. The resistivity of iridium is higher than that of copper, meaning it offers more resistance to the flow of current. However, in applications where the highest conductivity is not the primary requirement, iridium’s other physical characteristics make it the superior choice.
How Iridium’s Physical Properties Enhance Its Electrical Use
Iridium’s utility as a conductor is enhanced by its extreme physical resilience, which allows it to function reliably in environments that would destroy most other conductive materials. Its high melting point, approximately 2,446°C, provides thermal stability. This ensures the metal maintains its electrical integrity and structural form in high-temperature systems.
Iridium is also the most corrosion-resistant metal known. It is inert to virtually all acids and reactive chemicals, including aqua regia, even at elevated temperatures. This chemical inertness is a significant advantage for electrical components, such as contacts and electrodes, that must operate continuously in harsh, reactive chemical environments.
Key Applications Utilizing Iridium’s Conductivity
The combination of iridium’s electrical conductance and extreme durability makes it indispensable in high-performance industries. A prime example is its use in high-performance spark plug electrodes. In a combustion engine, resistance to heat erosion and chemical wear allows the iridium tip to maintain a precise point for a strong spark over long service intervals.
Iridium is also used for specialized electrical contacts in electronic components and industrial machinery. Its resistance to arc erosion, the physical damage caused by electrical arcing, makes it ideal for contacts that must repeatedly open and close a circuit reliably. Furthermore, iridium alloys are employed in components designed for extreme temperature environments, such as parts within jet engines and aerospace electrical systems.