| Atomic Number: | 39 | Atomic Symbol: | Y |
| Atomic Weight: | 88.9059 | Electron Configuration: | 2-8-18-9-2 |
| Shells: | 2,8,18,9,2 | Filling Orbital: | 4d1 |
| Melting Point: | 1523oC | Boiling Point: | 3337oC |
| Uses: | For color TV screens |
History
(Ytterby, a villiage in Sweden near Vauxholm) Yttria, which is
an earth containing yttrium, was discovered by Johann Gadolin of Finland in
1794. Ytterby is the site of a quarry which yielded many unusual minerals
containing rare earths and other elements. This small town, near Stockholm,
bears the honor of giving names to erbium, terbium, and ytterbium as well as
yttrium.
In 1843 Mosander showed that yttira could be resolved into the oxides (or
earths) of three elements. The name yttria was reserved for the most basic one;
the others were named erbia and terbia.
Sources
Yttrium occurs in nearly all of the rare-earth minerals. Also
found in minerals such as monazite, xenotime and yittria. Analysis of lunar rock
samples obtained during the Apollo missions show a relatively high yttrium
content.
It is recovered commercially from monazite sand, which contains about 3%, and
from bastnasite, which contains about 0.2%. Wohler obtained the impure element
in 1828 by reduction of the anhydrous chloride with potassium. The metal is now
produced commercially by reduction of the fluoride with calcium metal. It can
also be prepared by other techniques.
Properties
Yttrium has a silver-metallic luster and is relatively stable
in air. Turnings of the metal, however, ignite in air if their temperature
exceeds 400C. Finely divided yttrium is very unstable in air.
Uses
Yttrium oxide is one of the most important compounds of yttrium and
accounts for the largest use. It is widely used in making YVO4 europium, and
Y2O3 europium phosphors to give the red color in color television tubes. Many
hundreds of thousands of pounds are now used in this application.
Yttrium oxide also is used to produce yttrium-iron-garnets, which are very
effective microwave filters.
Yttrium iron, aluminum, and gadolinium garnets, with formulas such as
Y3Fe5O12 and Y3Al5O12, have interesting magnetic properties. Yttrium iron garnet
is also exceptionally efficient as both a transmitter and transducer of acoustic
energy. Yttrium aluminum garnet, with a hardness of 8.5, is also finding use as
a gemstone (simulated diamond).
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.
Alloys with other useful properties can be obtained by using yttrium as an
additive. The metal can be used as a deoxidizer for vanadium and other
nonferrous metals. The metal has a low cross section for nuclear capture. 90Y,
one of the isotopes of yttrium, exists in equilibrium with its parent 90Sr, a
product of nuclear explosions. Yttrium has been considered for use as a
nodulizer for producing nodular cast iron, in which the graphite forms compact
nodules instead of the usual flakes. Such iron has increased ductility.
Yttrium is also finding application in laser systems and as a catalyst for
ethylene polymerization.
It also has potential use in ceramic and glass formulas, as the oxide has a
high melting point and imparts shock resistance and low expansion
characteristics to glass.
Isotopes
Natural yttrium contains but one isotope, 89Y. Nineteen other
unstable isotopes have been characterized.
Costs
Yttrium metal of 99.9% purity is commercially available at a cost
of about $75/oz.