Electron configuration and elemental properties of zirconium.
Electron configuration and elemental properties of zirconium.
Credit: Greg Robson/Creative Commons, Andrei Marincas Shutterstock
Atomic Number: 40
Atomic Symbol: Zr
Atomic Weight: 91.224
Melting Point: 3,371 F (1,855 C)
Boiling Point: 7,968 F (4,409 C)

Word origin: The word zirconium derives from the Persian zargun, meaning gold-like. Zircon, the primary gemstone mineral of zirconium, is also known as jargon, hyacinth, jacinth and ligure. Zircon, and its variations, is mentioned in the Bible.

Discovery: It was not known that zircon contained a new element until 1789, when Martin Heinrich Klaproth discovered it while analyzing a jargon from Ceylon. In 1824, Berzelius first isolated the impure metal by heating a mixture of potassium and potassium zirconium fluoride in a small decomposition process.

Properties of zirconium

Zirconium is a transition metal with a grayish-white luster. The solid metal is difficult to ignite, but when it is finely divided it may ignite spontaneously in air, especially at high temperatures. Its compounds have a low inherent toxicity. [See Periodic Table of the Elements]

Zirconium has a low absorption cross section for neutrons and so is used for nuclear energy applications. Zirconium is exceptionally resistant to corrosion by many common acids and alkalis, seawater and other agents. Alloyed with zinc, zirconium becomes magnetic at temperatures below 35 K (minus 238.1 C / minus 396.7 F).

Hafnium is always found in zirconium ores, and it is difficult to separate it out. Commercial-grade zirconium contains 1 to 3 percent hafnium. Reactor-grade zirconium has no hafnium.

Zircon (zirconium oxide) is the primary source of elemental zirconium.
Zircon (zirconium oxide) is the primary source of elemental zirconium.
Credit: Morgenstjerne Shutterstock

Natural zirconium contains five isotopes and fifteen others are known to exist.

Sources of zirconium

Zirconium is produced from the mineral zircon (ZrSiO4). Lunar rocks appear to have a surprisingly high zircon content compared to terrestrial rocks, according to analysis of lunar rock samples from the various Apollo missions. It is found abundantly in S-type stars and has been identified in the sun and meteorites. Zirconium can also be present in at least 30 other recognized mineral species.

Zirconium mineral deposits are found all over the world.

It is produced commercially by reduction of the chloride with magnesium, in addition to other methods.

Uses of zirconium

Zircon (or zirconium oxide) has a high index of refraction and is used as a gemstone — probably zirconium’s most well-known use. The impure oxide, zirconia, is used for laboratory crucibles that withstand heat shock, for metallurgical furnace linings, and for refractory materials in glass and ceramics. This use accounts for a large amount of all zirconium use in the world.

Zirconium is used in surgical appliances, in photoflash bulbs, as a getter in vacuum tubes, an alloying agent in steel, explosive primers, lamp filaments, rayon spinnerets, and much more. It is used in poison ivy lotions as a form of carbonate.

Zirconium is superconductive with niobium at low temperatures. In this state it is used to make superconductive magnets, and there is hope that these magnets could contribute to a large-scale generation of electric power.

Zircaloy, a patented alloy, was developed specifically for nuclear applications. Commercial nuclear power generation currently accounts for more than 90 percent of zirconium metal production. Commercial-sized reactors can use as much as a half-million linear feet of zirconium alloy tubing.

(Source: Los Alamos National Laboratory)