Tantalum/Niobium
Tantalum
was first discovered in 1801 with Niobium's discovery coming
soon after in 1802. For several years it was thought that
Niobium and
Tantalum were the same element until the mid nineteenth
century when they were proven to be separate elements. Of
the two, niobium is far more abundant in the earth's crust
than tantalum; nevertheless they almost always occur together.
Tantalum-rich ores are found in Australia, Brazil, Africa
and Canada while Niobium-rich ores are found in North America,
Brazil, Nigeria, Zaire, Congo, and Russia.
The largest applications for Tantalum
have been in the manufacturing of capacitors. Tantalum also
has other metal applications including filaments, wires,
acid-proof chemical equipment and Tantalum Carbide. Tantalum
also has ceramic, glass, and special alloy applications.
Niobium is used mainly as an alloying
addition to steel in the form of ferro-niobium. It also
is used for pipeline construction, structural applications,
and automotive and aerospace applications.
Zirconium
and Others
In 1789, Martin Heinrich Klaproth
discovered Zirconium
in the mineral zircon. The largest reserves can be found
today in Australia, North America, Brazil, and Asia. Zirconium
ores almost always occurs in nature with Hafnium, and the
separation of the two is somewhat difficult.
Zirconium metal is widely used
in nuclear applications. Since Zirconium is extremely resistant
to heat and corrosion, it is also used in surgical appliances,
lamp filaments, crucibles and linings. The oxide is also
used in the glass and ceramic industries as a refractory
metal.
Some other metal-based chemicals
used for advanced and performance applications are Gallium,
Germanium,
Magnesium,
Scandium,
Titanium,
and Zinc. These
products are used in industrial and research applications
ranging from alloys and ceramics to electronics and fiber
optics.
Cerium
Cerium was first discovered
in 1803 and is the most abundant of the rare earth elements.
Deposits of the most common cerium sources are monazite,
which exists in India, Brazil, Australia and Africa, and
bastnasite found in China and North America, which are typically
between 30-50% Cerium. Elemental Cerium is a soft, silvery
metal that is very reactive in air and will ignite with
the scrape of a knife. Cerium exists in either of two oxidation
states, Cerous (III) and Ceric (IV). Ceric salts such as
Cerium Ammonium Nitrate, (NH4)2Ce(NO3)6, are usually yellow
or orange while Cerous salts are typically white. Currently,
the most commercially popular Cerium compounds are Cerous
and Ceric Salts as well as Ceric Oxide.
Cerium metal is a prime component of Mischmetal, which is
used in the manufacture of pyrophoric alloys (such as ignition
flints for welding torches and lighters). The metal is also
finding use as an additive to the walls of self-cleaning
ovens as it helps prevent the collection of cooking residues.
The oxide is very commonly used in glass applications as
both a component and a decolorizing agent while it is also
finding vast use as a polishing medium as well. The sulfate
is used as a volumetric oxidizing agent in quantitative
analysis. Cerium is also used in the production of television
phosphors, auto-catalysts and petroleum refining.
Dysprosium
Discovered in 1886, Dysprosium
is named for the Greek word dysprositos, which means "hard
to get". True to its name, Dysprosium was not isolated
until 1950, sixty-four years after its discovery. Commercial
sources of Dysprosium are bastnasite ore found in China
and North America as well as the ionic clays found in Southern
China, with the latter containing a greater percentage of
the element at about 4-10%. Elemental Dysprosium exists
as a silvery-white metal that is stable in air and soft
enough to cut with a knife. Dysprosium is commonly available
in its lustrous metal form as well as its powdered oxide
form.
Dysprosium metal is used in
permanent magnets for use in audio speakers and industrial
applications as well as for magnetorestricitive alloys.
The metal can also be combined with Vanadium and other rare
earths to form an alloy used in laser manufacture. Dysprosium's
thermal neutron absorption cross-section and high melting
point make it ideal for combining with stainless steel in
nuclear applications. Along with other small applications,
Dysprosium oxide has found use in a nickel cement used for
cooling nuclear reactor rods.
Erbium
Erbium was first discovered
in its oxide form in Ytterby, Sweden in 1842 but was not
isolated in great purity until 1905. Commercial sources
are monazite ore found in India, Brazil, Australia and Africa,
bastnasite ore mined in China and North America and the
ionic clays of Southern China, which has the highest Erbium
content among the three, 2-5%. Erbium metal is lustrous
and silvery white with a very soft and malleable form. Erbium
metal oxidizes less quickly in air than other rare earth
metals, though it is similar in most other respects. The
oxide stands out amongst other rare earth oxides with its
unique pale pink color. Erbium metals and oxides are commonly
available in commercial markets.
Erbium metal has uses similar
to those of other rare earth metals such as metallurgy and
superconductors though special exclusive uses for the oxide
exist by virtue of its distinct color. Because of the pastel
pink color, due to its sharp absorption lines (common to
rare earth oxides), Erbium Oxide is used widely as a coloring
agent for glass and ceramics. The medical field has some
use for Erbium in as a dopant for lasers used in surgery.
The powdered oxide is also used in fiber optics and glass
for its ultraviolet absorbing capabilities.
Europium
Europium was discovered in
1890 when suspicious emission lines were observed in a sample
of Samarium and Gadolinium. Most credit its official discovery
to Demarcay who isolated a pure sample in 1901. Being the
most reactive of the rare earth elements, Europium is very
difficult to isolate and is separated from monazite ore
found in India, Brazil, Australia and Africa, bastnasite
ore found in China and North America and the ionic clays
of Southern China, all of which contain slight amounts of
Europium, 0-1%. Difficulty in separation and rarity make
Europium one of the most expensive rare earth elements,
though it is used in many common consumer goods.
Europium metal readily oxidizes
in air making it ideal for pyrophoric alloys, but because
lighter, cheaper rare earth metals boast similar properties
this market is sparse for Europium, which has few metal
applications. Europium has found its greatest use as a phosphor
activator and is widely used in europium-activated yttrium
compounds to produce red color in television, computer monitor
and LED displays. This application accounts for the vast
majority of Europium consumption worldwide. Europium is
also used to dope plastics in lasers.
Gadolinium
Gadolinium was first isolated
in 1880 and named for the Gadolinite ore that it was isolated
from (the ore itself is named for Finish chemist Gadolin).
Gadolinium is found in the monazite ores of India, Brazil,
Australia and Africa, bastnasite ores of China and North
America and is also refined from the ionic clays of Southern
China, all of which contain about 0-5%. Gadolinium metal
is similar to other rare earth metals aside from its unique
Curie temperature, which lies at just above room temperature.
The element also has the single highest thermal neutron
capture cross-section of any known element at 49,000 barns
and has found use in nuclear applications. Along with metal,
the oxide form is also readily available on the chemical
market.
Gadolinium metal is used to
enhance iron, chromium and similar alloys to increase their
resistance to oxidation at high temperatures. The metal
is also an unusually good superconductor, which also finds
its use in some special materials and alloys. Gadolinium
Yttrium Garnets are used in microwave applications and other
Gadolinium compounds are used in color television phosphors.
In the medical realm, solutions of gadolinium compounds
are used as intravenous contrasts to enhance images in patients
undergoing MRI (magnetic resonance imaging).
Gallium
Gallium was discovered in 1875
spectroscopically by Boisbuadran. Sources of Gallium are
diaspore, sphalerite, germanite, bauxite, and even coal,
though only in trace amounts. Elemental Gallium is an extremely
soft metal that is liquid at temperatures slightly higher
than room temperature (29.76oC). Similar to Mercury, though
not known to be as toxic, Gallium is very shiny and readily
alloys with other metals. Gallium has the longest liquid
temperature range of any metal and low vapor pressure even
at high temperatures. Commercially, Gallium is available
in oxide form.
Gallium can be used to wet glass
or porcelain and forms a brilliant mirror when applied to
glass. Some low melting point alloys have Gallium as a component.
Because of its low vapor pressure and predictable thermal
expansion, Gallium can be used in high-temperature thermometers.
Semiconductors are doped with Gallium. The compound Gallium
Arsenide can be used to transfer electricity directly into
coherent light. Large amounts of Gallium are used in space
research to detect solar neutrinos in experiments being
conducted in Italy and Russia.
Germanium
Germanium was discovered in
1886 by Winkler and named for the country Germany. Sources
of Germanium are argyrodite, germanite, zinc ores and even
coal. The element is commonly recovered from the flue dusts
of zinc smelters and the combustion of some coals. Elemental
Germanium is a brittle, crystalline metalloid that is relatively
stable and will not oxidize in air. Modern techniques allow
for the production of extremely pure Germanium. Germanium
has favorable conductive properties while the oxide finds
use due to its high index of refraction. Germanium is commercially
available in its oxide form.
Germanium's primary uses are
in the semiconductor industry and transistor manufacture
where it is often doped with gallium, arsenic and other
elements. It is also used in high-sensitivity infrared devices
because Germanium and its oxide are transparent to infrared
light. The oxide has a high refractive index and finds use
in special glasses for camera and microscope lenses. Germanium
is also used in the manufacture of Red-Fluorescing Phosphors,
dental alloys and electroplating while Organogermanium chemistry
is a becoming field of great commercial interest.
Holmium
Holmium was discovered in 1878
and named for Stockholm, the home city of its chemist discoverer.
Holmium exists in monazite ore found in India, Brazil, Australia
and Africa, bastnasite ore found in China and North America
as well as ionic clays found in Southern China, which contains
the most at about 2% Holmium. Elemental Holmium is a lustrous,
ductile metal with unusual magnetic properties. Holmium
has few large industrial applications but is commercially
available in oxide and metal forms.
Holmium is used as a dopant for
Yttrium-Aluminum Garnets used in laser surgery and is also
used in to quench nuclear chain reactions in fission reactors.
Holmium finds some use in alloy and phosphor production
as well as in filters for UV Spectrometer calibration.
Holmium is also popular among lighting
researchers and ceramics companies.
Lanthanum
Lanthanum was discovered in
an impure sample of cerium nitrate in 1839 and named for
the Greek word lanthanein, which means "to lie hidden".
Lanthanum exists in great amount in monazite ore found in
India, Brazil, Australia and Africa, bastnasite ore of China
and North America and can also be found in the ionic clays
of Southern China. Each of the major sources contain about
20-30% Lanthanum by weight. Similar to Cerium, Lanthanum
exists elementally as an extremely soft, luminous metal
that is readily oxidized in air and water and reacts with
elemental carbon, nitrogen, boron, selenium, silicon, phosphorus
and sulfur. Lanthanum is commercially available in metal,
oxide and several salt forms.
Lanthanum metal is used in many
applications similar to those of Cerium such as alloys and
flints. The metal is also used in the fabrication of nodular
cast iron. Lanthanum's favorable presence in fuel-cracking
catalysts have made a market for the plentiful rare earth
in the petroleum industry while it also finds use in the
glass market as a dopant to increase resistance to alkali
compounds. The most recent interest in Lanthanum has come
from its use in Hydrogen Sponge Alloys, which are an important
component of solid oxide fuel cells.
Lutetium
Lutetium was discovered in
1907 by three independent chemists in France, Germany and
New Hampshire (USA) from a material that Marignac had separated
and named "ytterbium". As one of the rarest of
the rare earth elements, Lutetium is available in very short
supply from bastnasite ore and Chinese ionic clay, which
each contain less than 0.5% Lutetium by weight. Lutetium's
abundance in any natural material correlates proportionally
to that of Yttrium as the two share many elemental similarities.
It is commercially available in its oxide and metal forms
though few industrial applications exist.
Lutetium's rarity and difficult
separation have hurt its chances with commercial success.
Some applications exist in the lighting phosphor industry
while others use Lutetium in cracking and polymerization
catalysts. While there is research being done on Lutetium's
use in specialty alloys, no large markets currently exist
for the heavy lanthanide.
Magnesium
Magnesium was discovered by
Joseph Black in 1755, but was not isolated in the pure metal
form until 1808. It is a ductile, silvery-white, chemically
active metal with a hexagonal close-packed crystalline structure
that becomes malleable when heated. Magnesium is the eighth
most abundant element in the Earth's crust but does not
occur uncombined in nature. It is found in abundance in
the minerals brucite, magnesite, dolomite, and carnalite
in China, Russia and Korea.
Magnesium compounds are used
in ceramics, cosmetics, fertilizers, insulation, leather
tanning, and textile processing. It is also found in asbestos,
meerschaum, serpentine, and talc. Magnesium chloride is
found in seawater, brines, and salt wells. Mineral waters
often contain salts of magnesium; the magnesium ion imparts
a bitter flavor. Magnesium is a constituent of the chlorophyll
in green plants and is necessary in the diet of animals
and humans. Magnesium is used extensively in alloys since
it can be easily machined, cast, forged, and welded. Magnesium
is used in jet-engine parts, rockets and missiles, luggage
frames, portable power tools, and cameras and optical instruments.
It is also used in photographic flashbulbs and is added
to some rocket and missile fuels. An important use is in
preventing the corrosion of iron and steel, as in pipelines
and ship bottoms.
Mixed
Rare Earth/Mischmetal
Mixtures of the several rare
earth elements refined into metals, oxides and salts are
commercially popular and have many applications. The mixtures
are typically made from the monazite ore of India, Brazil,
Australia and Africa or bastnasite ore of China and North
America. The elemental form of mixed rare earth is known
as Mischmetal and has lustrous and ductile characteristics
like those of its constituents. The other common forms;
carbonate, oxide, chloride and fluoride, exist as white
to brown/orange powders or crystal aggregates. The compositions
of all mixed rare earth materials are typically that of
the ore from which they were produced, often being primarily
made of Cerium, Lanthanum, Praseodymium and Neodymium. These
materials are usually more economical that other rare earth
products because less separation is required.
Mischmetal, being primarily
Cerium and Lanthanum, is popular in pyrophoric alloys used
in flints and lighters. Mischmetal is also used in many
specialty alloys. Mixed rare earth oxide is often used as
a polishing component. Mixed Rare earth salts and oxides
are popular in the auto catalyst and electronics industries.
In general, mixed rare earth products are an economical
option in applications that call simply for material with
characteristics shared by the lighter rare earth elements
such as reactivity or crystal structure. It is also common
for companies to purchase rare earth salts and oxides with
the intention of handling their separation themselves.
Neodymium
Neodymium was discovered in
1885 by von Welsbach when he separated the element from
a mix that was then known as Didymium. The sixtieth element
is found in monazite ore of India, Brazil, Australia and
Africa, bastnasite ore of China and North America as well
as in the ionic clays of Southern China, with each source
containing 0-20% Neodymium. Neodymium metal is one of the
more reactive rare earth metals and will oxidize quickly
when exposed to air. Neodymium compounds vary in color from
blue to purple to red and give the lanthanide some unique
commercial uses. Because of its presence in the various
forms of rare earth containing ores and clays, Neodymium
is popular in general lanthanide applications and can be
used to weight the strength of the rare earth market as
a whole. Neodymium is readily available in its metal and
oxide forms as well as several salts including carbonate
and nitrate.
Neodymium metal is used extensively
to produce Nd-Fe-B magnets, which have energy densities
as high as 27 to 35 million gauss oersteds. They are the
most compact magnets commercially available. Neodymium compounds
are extensively used in glasses and coatings for their unique
colors and ultraviolet absorption abilities. Welding goggles
are commonly darkened with didymium, a neodymium-containing
compound, and neodymium alone is used to color glass delicate
shades of red, blue, purple and gray. Neodymium's coloring
characteristics are used in applications ranging from small
artistic products to large mass-production. Neodymium is
also used widely in electronic, auto catalyst and rubber
catalyst applications.
Niobium
Niobium was discovered in 1801
in England from an ore sent there a century earlier from
the USA. For 100 years Niobium was also called Columbium
until it was made official in 1950, though some still refer
to it as Columbium. That name comes from columbite, one
of the major sources of Niobium found in North America,
Brazil, Nigeria, Zaire, Congo, and in Russia. Elemental
Niobium is a lustrous, soft metal and is quite ductile.
Niobium metal oxidizes in air at 200oC. The metal is superconductive
and can be used in special magnetic applications. Niobium
is commercially available in its metal and pentoxide forms.
Niobium is used in advanced
air-frame systems such as those used in the Gemini Space
Program and other aerospace products. Special superconductive
magnets are made with Niobium Zirconium wire, which retains
its conductivity even in strong magnetic fields. Niobium
is also popular in alloys and stainless steels and some
nonferrous alloys because its presence enhances the strength
of the material and is used in pipelines among other things.
Some nuclear applications exist because of Niobium's low
capture cross-section for thermal neutrons. Niobium pentoxide
is also used in some glass and ceramic applications.
Praseodymium
Praseodymium was extracted
from Didymium in 1885 and named for its green color (the
Greek word prasios means "green") by von Welsbach.
Praseodymium exists in moderately abundant amounts (1-5%)
in monazite ore of India, Brazil, Australia and Africa,
bastnasite ore found in China and North America as well
as in the ionic clays of Southern China. Praseodymium metal
is slightly less reactive in air than most rare earth metals.
Similar to Cerium, Praseodymium exists in the (III) oxidation
state as well as in the (IV) state though, unlike Cerium,
its oxide is generally a mix of the two to form Pr6O11.
Praseodymium compounds exhibit an array of different colors
from jet black to lime green. Like most rare earth elements
Praseodymium is commercially available in its metal, oxide
and carbonate forms.
Praseodymium is used in applications
common to rare earth elements. The metal is a modest constituent
of Mischmetal, which is an alloy of rare earth metals, primarily
cerium, lanthanum, praseodymium and neodymium. Mischmetal
is used in heat-conducting and pyrophoric alloys. Other
compounds of Praseodymium are used for their unique colors.
Praseodymium is mixed in glass along with other compounds
to produce a bright but smooth yellow color while Didymium,
a mix of Praseodymium and Neodymium (among others) is used
to color the glass in welding goggles. Praseodymium also
finds some use in lighting applications (like many rare
earth elements).
Samarium
Samarium was discovered in
the mineral samarskite in 1879 by Lecoq de Boisbaudran when
he observed some peculiarly sharp absorption lines. Only
recently has Samarium been isolated in pure form. Samarium
exists in monazite ore found in India, Brazil, Australia
and Africa, bastnasite ore of China and North America as
well as the ionic clays of Southern China, each containing
about 1-5% Samarium. The bright silver metal is soft and
ductile and reacts somewhat slower in air than most rare
earth metals. Samarium is commercially available in its
metal and oxide forms.
Samarium is popular in Samarium-Cobalt
magnets, which have the highest resistance to demagnetization
of any known material and intrinsic coercive force as high
as 2200 kA/m. Glass is often made to contain Samarium to
absorb infrared light and Calcium Fluoride crystals in laser
and masers are also doped with Samarium to enhance optical
performance. Compounds of the metal act as sensitizers for
phosphors excited in the infrared. The oxide exhibits catalytic
properties in the dehydration and dehydrogenation of ethyl
alcohol. Samarium is also used as a neutron absorber in
nuclear applications.
Scandium
Scandium was discovered in
1878 by Nilson. The metal was not extracted until 1937 and
it was until 1960 before the first pound of relatively pure
sample (99%) was produced. Scandium was originally found
in euxenite and gadolinite, but is more commonly collected
from the rare mineral thortveitite and Uranium mill tailings.
Scandium is believed to be a very common element in stars
such as the Sun, but is only the 50th most abundant element
on Earth and is distributed very widely among 800 different
earthly species of minerals. Elemental Scandium is a silver-white
metal that more resembles the rare earth metals than neighboring
Titanium or valence-shell-cousin Aluminum. It is a very
light metal and has a melting point much higher than that
of Aluminum. Scandium is commercially available in its metal
and oxide forms.
Scandium oxide is used for high-intensity
lights and Scandium iodide is added to Mercury vapor lamps
to produce highly efficient light sources that resemble
natural sunlight. The crude oil industry uses Scandium for
isotope tracing in refineries. Scandium metal is used in
alloys with Aluminum to produce many consumer products such
as baseball bats. The metal is also of interest to spacecraft
research because of its lightweight and high melting temperature.
Tantalum
Tantalum was discovered in
1802, though it was then thought that Niobium and Tantalum
were the same element. In the mid nineteenth century it
was proven that Tantalum and Niobium were separate elements.
Primary sources of Tantalum are columbite and tantalite
ores mined in Australia, Brazil, Africa and Canada, which
contain up to sixty percent Tantalum by weight. The separation
of tantalum from Niobium is quite difficult and involves
several steps. Elemental Tantalum is metallic, heavy, gray
and very hard. At temperatures below 150oC Tantalum is almost
completely immune to chemical attack. Only hydrofluoric
acid, acidic solutions containing the fluoride ion, and
free sulfur trioxide affect the metal at these temperatures.
Only two elements have higher melting points than Tantalum,
Tungsten and Rhenium. Tantalum is popular in its metal form
but is also commercially available in its pentoxide form
as well.
Tantalum metal has found many
uses in consumer and industrial markets in recent years.
The largest applications for Tantalum have been in the manufacture
of capacitors. Tantalum's high melting point and superconductive
properties have made it popular in many other metal applications
as well including filaments, wires, acid-proof chemical
equipment and Tantalum Carbide, one of the hardest materials
known to man. Several uses exist in the medical field as
well as Tantalum metal is nonirritating and immune to all
body liquids. Special alloy and single-crystal Tantalum
is used in the construction of aircraft parts and strong,
ductile steel. The ceramic industry has also found use for
Tantalum in dielectrics. Tantalum oxide is also used in
the manufacture of special refractive glass for optical
applications.
Terbium
Terbium was discovered in 1843
by Mosander and named for the Swedish city of its origin.
Commercial sources of Terbium are monazite ore found in
India, Brazil, Australia and Africa, bastnasite ore of China
and North America as well as the ionic clays of Southern
China, which yields the most Terbium at 0.5-1.5%. Elemental
Terbium is a soft, silvery metal that reacts in air slower
than most rare earth metals. Aside from its metal form,
Terbium is also commercially available in its oxide form,
which is a brown or dark red powder.
Terbium has many small applications,
but no large-scale industrial uses as of yet. It is used
as a dopant in calcium fluoride, calcium tungstate, and
strontium molybdate, which are used in solid-state devices.
The oxide has potential to be used as an activator in green
phosphors for television tubes. Sodium terbium borate is
used as a laser material and emits coherent light at 0.546
um. Also, Terbium can be used with ZrO2 as a crystal stabilizer
in high temperature fuel cells.
Thulium
Thulium was discovered in 1879
by the Swedish chemist Theodor Cleve and has not been available
in a pure elemental form until very recently. Thulium is
the rarest of the rare earth elements and is found in small
supply (<0.6%) amongst other lanthanides in monazite
ore found in India, Brazil, Australia and Africa, bastnasite
ore found in China and North America as well as in the ionic
clays of Southern China. The metal is soft, silvery and
does not react as quickly with air as other rare earth metals,
though it will oxidize. Despite its rarity, Thulium is commercially
available in its metal and oxide forms.
Due to its rarity and high-cost
little is known about the commercial potential of Thulium.
Like all lanthanides, Thulium metal is used in limited specialty
alloy applications and may be useful because of its nuclear,
conductive and magnetic properties. Thulium 169 that has
been bombarded in nuclear reactors may be used as a radiation
source in portable x-ray machines. Another possible application
is use in ceramic magnets (ferrites) for use in microwave
devices.
Titanium
Titanium was discovered in
1791 and named for the Titans of Greek mythology. Titanium
is the ninth most abundant element in the Earth's crust
and is found in the minerals rutile, ilmenite, titanates
and many iron ores. The element also exists in the human
body. Elemental Titanium is a lustrous white metal with
a low density, high strength and excellent corrosion resistance.
Titanium metal burns in air and is the only element to burn
in Nitrogen. Titanium exists in oxide form as a fine, white
powder. The oxide is readily available on commercial chemical
markets.
Titanium is important as an
alloying agent with aluminum, molybdenum, manganese, iron
and other metals. The aircraft, defense and aerospace industries
use Titanium in alloys because of its favorable strength,
weight and temperature resistance. Titanium is as strong
as steel but 45% lighter. Naval applications also exist
as result of Titanium's resistance to corrosion, namely
its immunity to salt water. Titanium oxide is, when pure,
rather clear and has a higher optical dispersion than diamond.
The oxide is used in many applications as a pigment because
of its indelible white color. Titanium oxide paints are
also very reflective of infrared light making them ideal
for solar observatories where heat affects viewing conditions.
Paint and dye applications account for the widest use of
Titanium.
Ytterbium
Ytterbium was discovered in
1878 in what was then known as Erbia. Ytterbium is produced
commercially from monazite ore found in India, Brazil, Australia
and Africa, bastnasite ore from China and North America
as well as from the ionic clays of Southern China, which
contains the highest concentration at 2-4%. Elemental Ytterbium
is a soft, silvery metal that is quite stable, though will
oxidize if left exposed to air or water for very long. The
metal exhibits typical metallic conductive properties, but
when brought to high pressure (>16,000 atm) at room temperature
the metal becomes a semiconductor. Ytterbium is commercially
available in its oxide and metal forms.
Few industrial applications
exist for Ytterbium probably due to its cost and rarity.
Stainless steel has shown increased grain refinement, strength
and other mechanical attributes when combined with small
amounts of Ytterbium. One isotope is believed to be useful
in portable x-ray devices for use when electricity is unavailable
(similar to Thulium). Ytterbium is used in limited phosphor
applications as well as in certain kinds of specialized
catalysts.
Yttrium
Yttria, an oxide ore that would
later be split into Yttrium, Terbium and Erbium, was discovered
in 1794 by the Finish chemist Gadolin. When the ore was
split in 1843, the name Yttrium was given to the simplest
of the resulting elements. Though Yttrium is neither a lanthanide
nor an actinide, it is considered a rare earth element because
of its similarity and natural proximity to the lanthanides.
Yttrium is present in monazite ore found in India, Brazil,
Australia and Africa, bastnasite ore from China and North
America and, in greater abundance, in the ionic clays of
Southern China. Elemental Yttrium is a soft, luminous metal
and is relatively stable in air, though shavings and small
pieces of the metal have been known to ignite at 400oC.
Yttrium oxide is the far more popular commercial form of
the element, though both it and the metal are readily available.
Yttrium Oxide has found many
uses in industrial and commercial products. Yttria is commonly
mixed with Europium to form (Y, Eu)VO4 and (Y, Eu)2O3 phosphors,
which produce the red color in television tubes. Several
different Yttrium garnets also call for the rare earth.
Yttrium-Aluminum garnet (with a hardness of 8.5) is used
as a synthetic diamond for technical applications including
lasers used in surgery and Yttrium-Iron garnets make useful
microwave filters. Other uses may also exist as Yttrium
Iron, Aluminum, and Gadolinium garnets, with formulas such
as Y3Fe5O12 and Y3Al5O12, have interesting magnetic properties.
Small amounts of Yttrium (0.1 to 0.2%) can be used to reduce
the grain size in Chromium, Molybdenum, Zirconium, and Titanium,
and to increase strength of Aluminum and Magnesium alloys.
The metal can be used as a deoxidizer for vanadium and other
nonferrous metals. Yttrium has also been explored as a nodulizer
for producing nodular cast iron, in which the graphite forms
compact nodules instead of the usual flakes increasing ductility.
Adding Yttrium to glass lends shock resistance and low expansion
characteristics, which make the element popular in glass
and ceramic applications as well.
Zinc
Zinc was officially discovered
in 1746 by Andreas Marggraf though it had been refined and
used for centuries dating back to prehistoric times. Chief
sources of zinc are the sulfide ore, zinc blende, or sphalerite,
zincite, an oxide; calamine, a silicate; and smithsonite,
the carbonate. The world's largest deposits of Zinc are
found in North America, China and Australia. Elemental Zinc
is a lustrous bluish-white metal. It is brittle and crystalline
at ordinary temperatures, but when heated it becomes ductile
and malleable. Zinc is a popular commercial product and
is readily available in several forms among those, oxide,
metal and sulfide.
Zinc is used principally for
galvanizing iron. It is also used for the negative plates
in certain electric batteries and for roofing and gutters
in building construction. Zinc compounds are used as a wood
preservative, in soldering fluxes, as a mordant in dyeing
textiles, and in adhesives and cements. Other compounds
serve as pigments, water softeners, and water purification
agents. Zinc is an important nutrient in bodily growth and
is a constituent of insulin used in the treatment of diabetes.
Zinc Sulfide is widely used in the manufacture of luminous
dials, X-ray and TV screens and fluorescent lights and Zinc
Chlorides and chromates are also commercially important
Zinc compounds.
Zirconium
Zirconium was discovered in
1789 by Klaproth in the mineral zircon, which had been known
for centuries and is mentioned in biblical writings though
it goes by many names. Today, the primary source of Zirconium
is zircon ore (ZrSiO4), which is found in Australia, North
America, Brazil and many parts of Asia. Natural Zirconium
ores almost always contain Hafnium and separation of the
two is somewhat difficult. Elemental Zirconium is a gray-white
lustrous metal that is relatively stable in air unless finely
divided and/or at high temperature. The metal is resistant
to most alkalis, acids, and seawater, among other compounds.
Zirconium is commercially available in its oxide form.
Zirconium metal is widely used
in nuclear applications because of Zirconium's low absorption
cross section for neutrons. The grade used in nuclear applications
is essentially free of Hafnium as the impurity introduces
undesirable nuclear characteristics. Zirconium is also used
in situations that require special corrosion resistance
such as surgical appliances and lamp filaments. Zirconium,
like Niobium, is superconductive at low temperatures, which
may be useful in the field of electricity generation. Zirconium
oxide is used in gemological applications when in pure form.
The impure oxide is used for shock and heat resistant crucibles
and linings. The oxide is also used in the glass and ceramic
industries as a refractory metal. This application uses
the largest share of the world's Zirconium
