Pure Zirconium
Zirconium Oxide
History
• Zirconium minerals have been around for a long time but
have been known as either jargon, jacinth, and hyacinth
• Martin Henrich Klaproth who lived between 1742 and
1817, isolated the oxide of zirconium from zircon in 1789
• Zirconium is 25% silica, 5% iron oxide, and 70% zirconia.
• Metallic zirconium was first prepared in 1824
by Jons J. Berzelius, a Swedish chemist.
• The zirconium-containing mineral zircon, or
its variations (jargon, hyacinth, jacinth, or
ligure), were mentioned in biblical writings
• The mineral was not known to contain a new
element until Klaproth analyzed a jargon from
the island of Ceylon in the Indian Ocean
• Pure zirconium wasn't prepared until 1914.
Jons J. Berzelium
Appearance
A lustrous, very corrosion resistant, gray-white,
strong transition metal that resembles titanium,
zirconium is obtained mainly from the mineral
zircon.
Characteristics
Zirconium is lighter than steel and its hardness is the same as
copper. When it is finely divided into a powder, zirconium can
spontaneously ignite in air, especially at high temperatures. The
Zirconium-zinc alloy becomes magnetic at temperatures below
35K. The oxidation state of zirconium is usually +4, although +3
and +2 can also be obtained in chemical compounds.
Zirconium is one of the more abundant elements, and is widely
distributed in the Earth's crust. Being very reactive chemically, it
is found only in the combined state. Under most conditions, it
bonds with oxygen in preference to any other element, and it
occurs in the Earth's crust only as the oxide, ZrO2 or as part of a
complex of oxides as in zircon, elpidite, and eudialyte.
Melting point: 1852°C
Boiling point: 4409°C
Density: 6.52g cm-3
Uses
Zirconium is primarily used in nuclear reactors,
especially in the cladding of the fuel rods, due to its
low neutron-capture cross-section and its resistance
to corrosion.
Zirconium is marketed as a natural gemstone used in
jewellery.
Zirconium oxide is processed to produce cubic
zirconia. This forms a brilliant clear crystal used as
a low-cost substitute for diamond.
Most of the zirconium used has been as compounds
for the ceramic industry: refractory, glazes,
enamels, foundry mold and core washes, abrasive
grits, and components of electrical ceramics, The
incorporation of zirconium oxide in glass
significantly increases its resistance to alkali.
Another significant use has been in photo flashbulbs.
Reactions
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Reaction of zirconium with air
Zirconium metal is coated with an oxide layer that usually renders it inactive.
However zirconium does burn in air if provoked to form thedioxide zirconium(IV)
oxide, ZrO2.
Zr(s) + O2(g) → ZrO2(s)
Reaction of zirconium with water
Zirconium does not react with water under normal conditions.
Reaction of zirconium with the halogens
Zirconium does react with the halogens upon warming to form zirconium(IV)
halides. So, zirconium reacts with fluorine, F2, chlorine, Cl2, bromine, I2, and
iodine, I2, to form respectively zirconium(IV) bromide, ZrF4, zirconium(IV)
chloride, ZrCl4, zirconium(IV) bromide, ZrBr4, and zirconium(IV) iodide, ZrI4.
Zr(s) + 2F2(g) → ZrF4(s) [white]
Zr(s) + 2Cl2(g) → ZrCl4(l) [white]
Zr(s) + 2Br2(g) → ZrBr4(s) [white]
Zr(s) + 2I2(g) → ZrI4(s) [white]
Reaction of zirconium with acids
Zirconium metal is coated with an oxide layer that usually renders it inactive. Most
cold mineral acids have little effect. Zirconium does dissolve in hydrofluoric acid,
HF, presumably to form fluoro complexes.
Reaction of zirconium with bases
Zirconium does not appear to react with alkalis under normal conditions, even
when hot.
Cubic Zirconium
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Cubic Zirconia is well known as a substitute for diamond, due to its high hardness and great
fire.
CZ is a beautiful synthetic gemstone that is durable and inexpensive and now even comes in any
color of the rainbow
Cubic Zirconia is a cubic form of zirconium oxide that is created in a laboratory, thus it is not a
mineral. However, it was found naturally occurring once at one site in the 1930's, but has yet
to be discovered since then.
Cubic Zirconia is an oxide of the metallic element zirconium, ZrO2. Each zirconium atom is
surrounded by eight oxygen atoms and each oxygen atom is connected to four zirconium
atoms. Mostly all CZ on the market also contains yttrium oxide that acts as a stabilizer. In
colored CZ, other oxides are added to produce the colors. Most CZ is about 87.5% zirconium
oxide and 12.5% yttrium oxide. Though these compounds are both opaque, white ores, they
melt together to form an amazing clear crystal.
To produce CZ, ZrO2 is heated to about 2300 degrees Celsius. This causes the mineral to
become isometric. However, this change is not permanent, it reverses upon cooling; which is
why a stabilizer must be added to prevent transformation upon cooling. If too much stabilizer is
added, it results in a softer, less brilliant product. This requires such high heat that a special
radio frequency "skull crucible" must be used to melt the zirconia powder. As the zirconia melts,
it leaves a thin shell that remains solid because it is cooled by the water in the copper fingers.
As this occurs the zirconia and the stabilizing oxide are added to fill the skull the desired level.
The contents are kept molten for several hours to ensure uniformity. To produce colors, oxides
of cerium, copper, titanium, iron, nickel, and many other elements are added also.