Appearance of Zirconium
A hard, silvery metal that is very resistant to corrosion.
Uses of Zirconium
Zirconium does not absorb neutrons, making it an ideal material to use in nuclear power stations. More than 90% of zirconium is used in this way. Nuclear reactors can have more than 100,000 meters of zirconium alloy tubing. With niobium, zirconium is superconductive at low temperatures and is used to make superconducting magnets.
Zirconium metal is protected by a thin oxide layer, making it exceptionally resistant to acid, alkalis, and seawater corrosion. For this reason, it is extensively used by the chemical industry.
Zirconium(IV) oxide is used in ultra-strong ceramics. It is used to make crucibles withstand heat-shock, furnace linings, foundry bricks, abrasives, and the glass and ceramics industries. It is so strong that even scissors and knives can be made from it. It is also used in cosmetics, antiperspirants, food packaging, and to make microwave filters.
Zircon is a natural semi-precious gemstone found in a variety of colors. The most desirable have a golden hue. The element was first discovered in this form, resulting in its name. Cubic zirconia (zirconium oxide) is a synthetic gemstone. The colorless stones, when cut, resemble diamonds.
Zircon mixed with vanadium or praseodymium makes blue and yellow pigments for glazing pottery.
Biological Role of Zirconium
Zirconium has no known biological role. It has low toxicity.
Natural Abundance of Zirconium
Zirconium occurs in about 30 mineral species, the major ones being zircon and baddeleyite. More than 1.5 million tonnes of zircon are mined each year, mainly in Australia and South Africa. Most baddeleyite is mined in Brazil.
Zirconium metal is produced commercially by first converting zircon to zirconium chloride and reducing the chloride with magnesium.
|
Zirconium Properties |
|
Atomic Number |
40 |
|
Atomic Mass |
91.22 g.mol -1 |
|
Electronegativity According To Pauling |
1.2 |
|
Density |
6.49 g.cm-3 at 20°C |
|
Melting point |
1852 °C |
|
Boiling point |
4400 °C |
|
Van der Waals Radius |
0.160 nm |
|
Ionic Radius |
0.08 nm (+4) |
|
Isotopes |
11 |
|
Electronic Shell |
[ Kr ] 4d2 5s2 |
|
Energy of First Ionization |
669 kJ.mol -1 |
|
Energy of Second Ionization |
1346 kJ.mol -1 |
|
Energy of Third Ionization |
2312 kJ.mol -1 |
|
Energy of Fourth Ionization |
3256 kJ.mol -1 |
|
Discovered by |
Martin Klaproth in 1789 |
Applications of Zirconium
Zirconium is used in alloys such as zircaloy, which is used in nuclear applications since it does not readily absorb neutrons. It is also used in catalytic converters, percussion caps, and furnace bricks. Baddeleyite and impure zirconium (zirconia) are used in lab crucibles.
The major usage of zircon (ZrSiO4) is refractories, ceramic opacification, and foundry sands. Zircon is also marketed as a natural gemstone used in jewelry. The metal also has many other usages, among them in photographic flashbulbs and surgical instruments, to make the glass for television, in the removal of residual gases from electronic vacuum tubes, and as a hardening agent in alloys, especially steel. The paper and packaging industries find that zirconium compounds make suitable surface coatings because they have excellent water resistance and strength.
Health Effects of Zirconium
Zirconium and its salts generally have low systemic toxicity. The estimated dietary intake is about 50 micro g. Most passes through the gut without being absorbed, and that which is absorbed tends to accumulate slightly more in the skeleton than in tissue.
Zirconium 95 is one of the radio-nuclides involved in atmospheric testing of nuclear weapons. It is among the long-lived radionuclides produced and will continue to produce increased cancer risk for decades and centuries to come.
Environmental Effects of Zirconium
Zirconium is unlikely to present a hazard to the environment.
While aquatic plants have a rapid uptake of soluble zirconium, land plants have little tendency to adsorb it, and indeed 70% of plants that have been tested showed no zirconium to be present at all.
