Tantalum (previously known as tantalium (/tænˈtæliəm/, tan-TAL-ee-əm)) is a chemical
element with the symbol Ta
and atomic
number 73. A rare, hard, blue-gray, lustrous transition
metal, tantalum is highly corrosion resistant and occurs naturally in the mineral tantalite,
always together with the chemically similar niobium. It is
part of the refractory metals group, which are
widely used as minor component in alloys.
detailed description:
The
chemical inertness of tantalum makes it a valuable substance for laboratory
equipment and a substitute for platinum, but its main use today is in tantalum capacitors in electronic
equipment.
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History
Tantalum
was discovered in Sweden
in 1802 by Anders Ekeberg. One year earlier, Charles
Hatchett had discovered the element columbium. In
1809, the English chemist William Hyde Wollaston compared the oxides
derived from both columbium—columbite, with a density 5.918 g/cm3, and
tantalum—tantalite,
with a density 7.935 g/cm3, and concluded that the two oxides,
despite their difference in measured density, were identical. He decided to
keep the name tantalum. After Friedrich Wöhler confirmed these results, it was thought
that columbium and tantalum were the same element. This conclusion was disputed
in 1846 by the German chemist Heinrich
Rose, who argued that there were two additional elements in the tantalite
sample, and he named them after the children of Tantalus:
niobium (from Niobe,
the goddess of tears), and pelopium (from Pelops). The
supposed element "pelopium" was later identified as a mixture of
tantalum and niobium, and it was found that the niobium was identical to the
columbium already discovered in 1801 by Hattchet.
The
differences between tantalum and niobium were demonstrated unequivocally in
1864 by Christian Wilhelm Blomstrand, and Henri Etienne Sainte-Claire Deville,
as well as by Louis J. Troost, who determined the
empirical formulas of some of their compounds in 1865. Further confirmation
came from the Swiss chemist Jean Charles Galissard de Marignac,
in 1866, who proved that there were only two elements. These discoveries did
not stop scientists from publishing articles about the so-called ilmenium
until 1871. De Marignac was the first to produce the metallic form of tantalum
in 1864, when he reduced
tantalum chloride by heating it in an atmosphere of hydrogen. Early
investigators had been only able to produce impure tantalum, and the first
relatively pure ductile metal was produced by Werner von Bolton in 1903. Wires made
with metallic tantalum were used for light bulb
filaments until tungsten
replaced it in widespread use.
The
name tantalum was derived from the name of the mythological Tantalus, the
father of Niobe in
Greek
mythology. In the story, he had been punished after death by being
condemned to stand knee-deep in water with perfect fruit growing above his
head, both of which eternally tantalized him. (If he bent to drink the
water, it drained below the level he could reach, and if he reached for the
fruit, the branches moved out of his grasp.) Ekeberg wrote "This metal I
call tantalum … partly in allusion to its incapacity, when immersed in
acid, to absorb any and be saturated."
For
decades, the commercial technology for separating tantalum from niobium
involved the fractional crystallization of potassium heptafluorotantalate away
from potassium oxypentafluoroniobate monohydrate, a process that was discovered
by Jean Charles Galissard de Marignac
in 1866. This method has been supplanted by solvent extraction from
fluoride-containing solutions of tantalum.
PRICE
$125/KG
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