What Is Zinc?

Zinc is a metallic element (atomic number 30, symbol Zn) with properties that make it important across electrical engineering, materials science, and semiconductor technology. It is a moderately good electrical conductor with a resistivity of approximately 59 nanoohm-meters at 20 °C, as recorded in NIST data on the electrical resistivity of selected elements, and it has a hexagonal close-packed crystal structure that contributes to its mechanical ductility. Zinc occupies an established role in corrosion protection, battery electrochemistry, die-cast alloys, and compound semiconductor materials, placing it at the intersection of electrical, mechanical, and materials engineering disciplines.

Corrosion Protection and Galvanizing

Zinc's most widespread engineering application is as a sacrificial coating for steel, a process known as galvanizing. Because zinc's electrochemical potential is lower than that of iron, it acts as a sacrificial anode in galvanic couples: zinc corrodes preferentially, protecting the underlying steel even when the coating is scratched and the substrate is exposed. NIST research on the corrosion resistance of zinc-coated iron and steel established the performance parameters that underpin modern galvanizing specifications. Hot-dip galvanizing, in which fabricated steel components are immersed in molten zinc at approximately 450 °C, deposits a coating that adheres through a series of zinc-iron intermetallic phases. Galvanized steel is used in structural members, utility poles, automotive body panels, and marine infrastructure.

Zinc in Compound Semiconductors

In semiconductor technology, zinc is a constituent of several compound semiconductors used in optoelectronic and radiation-detection devices. Zinc selenide (ZnSe) and zinc sulfide (ZnS) are direct-bandgap II-VI semiconductors used in blue and ultraviolet light-emitting devices. Cadmium zinc telluride (CdZnTe or CZT) is a ternary compound in which the zinc fraction controls the bandgap, tuning it from the 1.44 eV of pure CdTe to higher values. CZT is one of the leading materials for room-temperature semiconductor radiation detectors because its wide bandgap enables high-resistivity bulk material, suppressing thermal noise without cryogenic cooling. IEEE research on CdZnTe semiconductor radiation detectors has demonstrated resistivities exceeding 10^9 ohm-centimeters in lead-doped crystals, performance that enables gamma-ray spectrometry at energies relevant to nuclear medicine and security screening.

Zinc in Batteries and Electrochemistry

Zinc is the negative electrode (anode) in several commercial battery chemistries, including the zinc-carbon and alkaline cells that power portable electronics, as well as the zinc-air battery, which achieves high energy density by using atmospheric oxygen as the positive reactant. Zinc's high electrochemical capacity (820 mAh per gram), combined with its low cost and low toxicity relative to alternatives such as lead and cadmium, has made it the subject of renewed research for grid-scale energy storage in rechargeable zinc-ion and zinc-air configurations. Die-cast zinc alloys (primarily Zamak alloys, based on zinc with aluminum, magnesium, and copper additions) provide near-net-shape structural components for electrical housings, connector bodies, and hardware.

Applications

Zinc has applications in a range of engineering and scientific fields, including:

• Corrosion protection for steel structures, vehicles, and utility infrastructure via galvanizing
• Room-temperature radiation detectors using cadmium zinc telluride (CZT) crystals
• Optoelectronic devices based on zinc selenide and zinc sulfide compound semiconductors
• Primary and rechargeable battery electrodes (alkaline, zinc-air, and zinc-ion cells)
• Die-cast housings and connector components in electrical and electronic assemblies