Zirconium (40)

Zirconium is a greyish-white lustrous metal. The finely divided metal can ignite spontaneously in air, especially at elevated temperatures. The solid metal is much more difficult to ignite. The inherent toxicity of zirconium compounds is low. Hafnium is invariably found in zirconium ores, and the separation is difficult. Commercial grade zirconium contains from 1 to 3% hafnium. The hafnium is removed from the zirconium used in the nuclear power industry.

Zirconium is found in S-type stars, and has been identified in the sun and meteorites. Analyses of lunar rock samples show a surprisingly high zirconium oxide content as compared with terrestrial rocks. Some forms of zircon (ZrSiO4) have excellent gemstone qualities.

•Name: Zirconium
•Symbol: Zr
•Atomic number: 40
•Atomic weight: 91.224 (2)
•Standard state: solid at 298 K
•CAS Registry ID: 7440-67-7
•Group in periodic table: 4
•Period in periodic table: 5
•Block in periodic table: d-block
•Color: silvery white
•Classification: Metallic

Historical information
Zirconium was discovered, in its impure form, by Martin Heinrich Klaproth at 1789 in Berlin, Germany. Origin of name is from the Arabic word "zargun" meaning "gold color," which describes the color of the gemstone now known as zircon (ZrSiO4). The minerals jargon, hyacinth, and jacinth also contain zircon and these have been known since biblical times and are mentioned in the bible in several places. The existence of a new element within these minerals was not suspected until studies by Martin Heinrich Klaproth in the late 18th century.

The impure metal was first isolated by Jöns Jacob Berzelius in 1824 who heated a mixture of potassium and potassium zirconium fluoride together in an iron tube. Pure zirconium was first prepared in 1914.

Physical properties
•Melting point: 2128 [or 1855 °C (3371 °F)] K
•Boiling point: 4682 [or 4409 °C (7968 °F)] K
•Density of solid: 6511 kg m-3

Orbital properties
•Ground state electron configuration: [Kr].4d2.5s2
•Shell structure: 2.8.18.10.2
•Term symbol: 3F2

Isolation
Zirconium is available from commercial sources so preparation in the laboratory is not normally required. In industry, reduction of ores with carbon is not a useful option as intractable carbides are produced. As for titanium, the Kroll method is used for zirconium and involves the action of chlorine and carbon upon baddeleyite (ZrO2). The resultant zirconium tetrachloride, ZrCl4, is separated from the iron trichloride, FeCl3, by fractional distillation. Finally ZrCl4 is reduced to metallic zirconium by reduction with magnesium (Mg). Air is excluded so as to prevent contamination of the product with oxygen or nitrogen.

ZrO2 + 2Cl2 + 2C (900°C) → ZrCl4 + 2CO

ZrCl4 + 2Mg (1100°C) → 2MgCl2 + Zr

Excess magnesium and magnesium dichloride is removed from the product by treatment with water and hydrochloric acid to leave a zirconium "sponge". This can be melted under helium by electrical heating.

FUN FACTS!
•Australia, Brazil, India, Russia and the USA are the major locations where zirconium deposits are found.
•It is abundant in S-type stars and its existence has also been detected in the Sun and the meteorites.
•The abundance of this metal in lunar rock samples has been found to be higher than what is found in terrestrial rocks.
•As a transition metal, zirconium is a good conductor of heat and fire. It also scores well on malleability and ductility.
•The metal has an atomic radius (pm) of 160 and Ionic radius of 790(+4e).
•Its lattice structure is hexagonal, and it has a lattice constant of 3.230.
•Specific heat is 0.281 @20°C J/g mol, and fusion heat is 19.2 (kJ/mol).
•Zirconium in powder form is highly susceptible to combustion, however, far less when in solid form.
•Alkalis, acids, salt water and many other agents have no corrosive effects on zirconium. However, if combined with hydrochloric and sulfuric acid, it will dissolve. This reaction becomes faster in the presence of fluorine.
•Inhalation of the compounds of this metal may cause skin and lung granulomas (a tumor composed of granulation tissue resulting from injury or inflammation or infection). Minor skin irritation has also been reported due to contact with zirconium powder. If it comes in contact with eyes, then it may warrant medical attention.
•The metal attains the property of a superconductor (a conductor that offers zero resistance to current; for this it must attain a certain temperature called the "critical temperature") when alloyed with niobium (soft, gray, ductile transition metal - more to come soon).
•The metal shares similar properties with titanium. However, the former has higher density and melting temperature than that of the latter.

Uses for Zirconium

# Zirconium is the source of the closest mimic of diamond - Cubic Zirconia (CZ). It is popularly fashioned as a diamond simulant (non-diamond material).

# Given the metal's low absorption of neutrons, and significant resistant towards heat and chemical corrosion, it is widely used in the working of nuclear reactors. Here the metal is used to provide an outer covering to components such as the fuel rods that run the reactor. As a matter of fact the nuclear power industry exploits 90% of the metal produced each year.

# As the metal is extremely high on the corrosion-resistance factor, it finds its applications in many industries which make use of corrosive agents such as in high-performance pumps, valves, etc.

# Zirconium oxide or zirconia, is mainly used in the manufacture of ceramic materials. It is an inorganic metal oxide, and a compound of zirconium. It is also used as a gemstone as it has a high refractive index.

# The main sources of zirconium are the minerals called zircon (ZrSiO4) and baddeleyite (ZrO2). A process known as the Kroll process is applied to obtain the metal from these minerals.

# Another use of zirconium is evident by black zirconium rings. These rings are available in elegant and luxurious designs for fashion-conscious people. These rings are scratch-resistant and do not sustain the wear and tear unlike other common metals.

# A common ingredient in antiperspirant is aluminum zirconium. It is, however, related to the development of breast cancer and Alzheimer's Disease. But there is no solid evidence to back this fact, and there are many controversies regarding the ill effects of the same.

# Zirconium also finds its application in steel as an alloying agent. Vacuum tubes, different surgical appliances, lamp filaments, piping, artificial joints and limbs require this metal. Apart from these, the metal is employed in photoflash bulbs, explosive primers, rayon spinnerets, etc.