Introduction
Zirconium is a transition metal present in group number 4 of the periodic table. Its atomic number is 40 whereas its atomic weight is 91.2. Zirconium has 40 electrons. It has 40 protons and 50 neutrons in its nucleus. Zirconium is represented by the symbol “Zr”.
Naming and History
The name of zirconium is derived from the Persian or Arabic word “Zargun” which means “gold or gold-colored”.
Zirconium is known from ancient times. It was used in precious stones such as hyacinth and zircon.
- Martin Heinrich Klaproth
Zirconium was first identified as an element by Martin Heinrich Klaproth in 1789, in Berlin, in a sample of zircon (zirconium silicate) from Sri Lanka. His evaluation of the mineral’s structure showed: 25% silica; 0.5% iron oxide; 70% new unidentified oxide. He called the new oxide ‘Zirconerde.’
- Sir Humphry Davy
In 1808, in London, Sir Humphry Davy attempted to obtain the pure metal from its oxide by electrolysis. However, he was not successful.
- Jacob Berzelius
Jacob Berzelius was the one who finally separated the metal in 1824, in Stockholm, Sweden. Berzelius heated an iron tube having a blend of potassium as well as potassium zirconium fluoride (K2ZrF6). He produced zirconium as an amorphous black powder.
- Anton Eduard and Hendrik de Boer
Dutch scientists Anton Eduard van Arkell and Jan Hendrik de Boer discovered an approach for producing high-purity zirconium in 1925. Zirconium tetraiodide (ZrI4) is decomposed on a white-hot tungsten filament producing a crystal bar of pure zirconium. This is called the crystal bar process.
Occurrence of Zirconium
Zirconium does not exist in its free elemental state. It is more abundant than copper and zinc. It is ten times in abundant than lead. The major ores containing zirconium are zircon, Kosnarite, Baddeleyite, Eudialyte, etc.
The main suppliers of Zirconium to the world are Australia, Sri Lanka, Brazil, and South Africa.
Properties of Zirconium
Zirconium is a silverish-grey, malleable, ductile, lustrous, and strong transition metal. It has a striking resemblance to titanium. It is very resistant to corrosion and heat. Zirconium is lighter than steel and harder than copper.
It does not dissolve in acids except hydrogen fluoride. Powdered zirconium spontaneously ignites in the air and is considered to be very dangerous. When zirconium is exposed to air, it forms a protective coating of oxide to prevent corrosion.
The melting point of zirconium is 1855°C and its boiling point is 4409°C. it exists as solid at room temperature. It has a density of 6.52 grams per cubic centimeter.
Zirconium in Biological Systems
Zirconium has no known significant role in living organisms. It has very low toxicity. This is not regarded as carcinogenic. But long-term exposure to zirconium powder can cause skin irritation in some people.
Uses of Zirconium
- It has the unique property that it does not absorb neutrons. That’s why it is used in nuclear power stations. 90% of zirconium is used in nuclear reactors.
- Zirconium is widely used in catalytic converters or catalysts such as in amination, hydrogenation, percussion caps or furnace bricks.
- It is used to remove traces of oxygen and other residual gases from vacuum tubes.
- Zirconium carbonate is used to treat poison ivy.
- It is alloyed with steel as a hardening agent and used in the manufacturing of some surgical equipment.
- Zircon – a transparent gemstone is used in jewelry.
- It is used in super magnets.
- Lithium zirconate is used to absorb carbon dioxide.
- It is used in heat exchangers, pipe fittings, etc.
- Zirconium is also used in photographic films and glass of television.
Isotopes of Zirconium
There are 5 isotopes of zirconium. The most abundant isotope of zirconium is Zr- 90 which has 51% of abundance.