Overview

Hafnium was discovered in 1923 by the Dutch physicist Dirk Coster and the Hungarian chemist George de Hevesy, working in Copenhagen in Niels Bohr's institute. They named it after Hafnia, the Latin name for Copenhagen. Hafnium is a shiny, silvery, corrosion-resistant metal, chemically almost inseparable from zirconium, and valued for its great appetite for neutrons, which makes it ideal for nuclear-reactor control rods. Chemically the twin of zirconium but its opposite in the hunger for neutrons, hafnium is used in the control rods of submarine and other reactors, in super heat-resistant alloys for rocket nozzles, and in the insulating layers of advanced computer chips.

Hafnium oxide's most consequential modern role came in 2007, when Intel introduced it as the high-k gate dielectric in its 45-nanometre transistors, a change credited with keeping Moore's Law on track after conventional silicon dioxide insulating layers had become too thin to prevent damaging current leakage; the switch to hafnium-based gates is now standard across the semiconductor industry's most advanced chips. Every major chipmaker producing leading-edge processors has since adopted some form of hafnium-based gate stack, making this dense, reactor-grade metal an unlikely but essential ingredient of the smartphone in most pockets.